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Nuts and seeds consumption and risk of cardiovascular disease, type 2 diabetes and their risk factors: a systematic review and meta-analysis.
Arnesen, EK, Thorisdottir, B, Bärebring, L, Söderlund, F, Nwaru, BI, Spielau, U, Dierkes, J, Ramel, A, Lamberg-Allardt, C, Åkesson, A
Food & nutrition research. 2023;67
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Nuts and seeds consumption is associated with a reduced risk of coronary heart disease (CHD) and cardiovascular disease (CVD). Nuts and seeds contain beneficial components to reduce the risk of CVD and CHD; hence dietary addition may benefit heart health. This systematic review and meta-analysis included sixty studies to analyse the effects of the consumption of nuts and seeds on the incidence of mortality from type 2 diabetes (T2D) and CVD and intermediate cardiometabolic risk factors. High nuts and seed consumption showed a 19% reduction in CVD risk and a 23% reduction in CVD mortality. In addition, high consumption lowered the risk of CHD by 25%. Increased nut consumption up to 30 g/day showed a dose-dependent relationship with reduced risk of CVD. Healthcare professionals can use the results of this study to understand the association between nuts and seeds consumption and CHD, CVD and blood lipid levels. However, further robust studies are required to evaluate the effect of specific nuts and seeds on CHD and CVD risk reduction.
Abstract
OBJECTIVES We aimed to systematically review studies and evaluate the strength of the evidence on nuts/seeds consumption and cardiometabolic diseases and their risk factors among adults. METHODS A protocol was pre-registered in PROSPERO (CRD42021270554). We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials and Scopus up to September 20, 2021 for prospective cohort studies and ≥12-week randomized controlled trials (RCTs). Main outcomes were cardiovascular disease (CVD), coronary heart disease (CHD), stroke and type 2 diabetes (T2D), secondary total-/low density lipoprotein (LDL)-cholesterol, blood pressure and glycaemic markers. Data extraction and risk of bias (RoB) assessments (using RoB 2.0 and RoB-NObS) were performed in duplicate. Effect sizes were pooled using random-effects meta-analyses and expressed as relative risk (RR) or weighted mean differences with 95% confidence intervals (CI); heterogeneity quantified as I 2. One-stage dose-response analyses assessed the linear and non-linear associations with CVD, CHD, stroke and T2D. The strength of evidence was classified per the World Cancer Research Fund criteria. RESULTS After screening 23,244 references, we included 42 papers from cohort studies (28 unique cohorts, 1,890,573 participants) and 18 RCTs (2,266 participants). In the cohorts, mainly populations with low consumption, high versus low total nuts/seeds consumption was inversely associated with total CVD (RR 0.81; 95% CI 0.75, 0.86; I 2 = 67%), CVD mortality (0.77; 0.72, 0.82; I 2 = 59.3%), CHD (0.82; 0.76, 0.89; I 2 = 64%), CHD mortality (0.75; 0.65, 0.87; I 2 = 66.9%) and non-fatal CHD (0.85; 0.75, 0.96; I 2 = 62.2%). According to the non-linear dose-response analyses, consumption of 30 g/day of total nuts/seeds was associated with RRs of similar magnitude. For stroke and T2D the summary RR for high versus low intake was 0.91 (95% CI 0.85, 0.97; I 2 = 24.8%) and 0.95 (0.75, 1.21; I 2 = 82.2%). Intake of nuts (median ~50 g/day) lowered total (-0.15 mmol/L; -0.22, -0.08; I 2 = 31.2%) and LDL-cholesterol (-0.13 mmol/L; -0.21, -0.05; I 2 = 68.6%), but not blood pressure. Findings on fasting glucose, HbA1c and insulin resistance were conflicting. The results were robust to sensitivity and subgroup analyses. We rated the associations between nuts/seeds and both CVD and CHD as probable. There was limited but suggestive evidence for no association with stroke. No conclusion could be made for T2D. CONCLUSION There is a probable relationship between consumption of nuts/seeds and lower risk of CVD, mostly driven by CHD, possibly in part through effects on blood lipids. More research on stroke and T2D may affect the conclusions. The evidence of specific nuts should be further investigated.
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Comparative effects of vitamin and mineral supplements in the management of type 2 diabetes in primary care: A systematic review and network meta-analysis of randomized controlled trials.
Xia, J, Yu, J, Xu, H, Zhou, Y, Li, H, Yin, S, Xu, D, Wang, Y, Xia, H, Liao, W, et al
Pharmacological research. 2023;188:106647
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Type 2 diabetes mellitus (T2DM), characterised by sustained hyperglycaemia and insulin resistance, remains a severe driver of chronic metabolic diseases such as cardiovascular diseases. The aim of this study was to investigate and compare the efficacy of vitamin and mineral supplements in the management of glycaemic control and lipid metabolism for type 2 diabetic patients to inform clinical practice. This study is a systematic review and meta-analysis of one hundred and seventy articles with a total of 4223 adults with T2DM. Participants were randomised to either the placebo/no treatment group (n= 6345) or to the treatment group (n= 7878). Results show that: - chromium was the most effective micronutrient for decreasing fasting blood glucose and insulin resistance. - vitamin K was the top-ranked micronutrient in reducing haemoglobin A1C and fasting insulin levels. - vanadium was the top-ranked micronutrient in total cholesterol reductions. - niacin was ranked as the most effective in triglycerides reductions and increasing high-density lipoprotein cholesterol levels. - vitamin E was the top-ranked micronutrient in low-density lipoprotein cholesterol reductions. Authors conclude that micronutrient supplements especially chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be more effective in the management of T2DM compared with other micronutrients.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Clinicians could consider the adjunctive effect of micronutrients supplements, such as chromium, vitamin E, vitamin K, vanadium, and niacin supplements in a nutrition protocol to manage T2DM and slow or prevent its complications.
- The study authors state that the vitamin and mineral supplements under review had a statistically significant improvement, however they did not reach the study threshold for clinical significance. Therefore they advise caution in utilising micronutrient supplements in the management of glucose and lipid metabolism for T2DM.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Objectives
The aim of this systematic review was to evaluate the comparative effects of vitamin and mineral supplements on managing glycemic control and lipid metabolism for type 2 diabetes mellitus (T2DM).
Methodology
This systematic review is registered with PROSPERO and adhered to PRISMA-2020 guidelines for network meta-analysis
The Cochrane Collaboration’s risk-of-bias tool was used to assess eligible randomised trials
8 prespecified markers identified and assessed in this study : 1) HbA1c (%), 2) fasting blood glucose (mmol/L), 3) total cholesterol (mmol/L), 4) triglycerides (mmol/L), 5) fasting insulin (μIU/mL), 6) HOMA-IR, 7) LDL-c (mmol/L), and 8) HDL-c (mmol/L).
Results
- 170 RCT trials of 14223 participants with T2DM treated with vitamin supplements, mineral supplements, or placebo/no treatment were included
- Low to very low certainty evidence established chromium supplements as the most effective in reducing fasting blood glucose levels and homeostasis model assessment of insulin resistance (SUCRAs: 90.4% and 78.3%, respectively)
- Vitamin K supplements ranked best in reducing glycated haemoglobin A1c and fasting insulin levels (SUCRAs: 97.0% and 82.3%, respectively), with moderate to very low certainty evidence
- Vanadium supplements ranked best in lowering total cholesterol levels with very low evidence certainty (SUCRAs:100%)
- Niacin supplements ranked best in triglyceride reductions and increasing high-density lipo-protein cholesterol levels with low to very low evidence certainty (SUCRAs:93.7% and 94.6%, respectively)
- Vitamin E supplements ranked best in reducing low-density lipoprotein cholesterol levels with very low evidence certainty (SUCRAs:80.0%).
Conclusion
- Micronutrient supplements, such as chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be efficacious in managing T2DM
- It should be noted that the evidence certainty for all was low.
Clinical practice applications:
- Chromium plays an important role in carbohydrate and lipid metabolism and was the most effective micronutrient for decreasing fasting blood glucose, HbA1c, fasting insulin, and HOMA-IR reductions. More pronounced effects were seen for chromium than vitamin E, vitamin C, niacin, selenium, and magnesium supplements
- Vitamin K was the top-ranked micronutrient in reducing HbA1c and fasting insulin levels. The mechanism through which Vitamin K affects glucose metabolism is proposed as activation of the AMP-activated protein kinase/sirtuin 1, that in turn increases phosphocreatine 3-kinase and glucose transporter 2 to decrease insulin resistance and fasting glucose.
- Vanadium was the top-ranked micronutrient in total cholesterol (TC) reductions, where supplementation dosage should be carefully considered, as vanadium compounds can be moderately or highly toxic. Vanadium supplementation is only recommended in cases of vanadium deficiency or diabetes, hyperlipidemia, and hypertension, where the intake of vanadium from food should be enhanced in preference to supplementation
- Niacin was ranked as the most effective in triglyceride (TG) reductions and increasing HDL cholesterol levels. The dose of niacin could not be determined
- Vitamin E was the top-ranked micronutrient in low-density lipo- protein (LDL) cholesterol reductions.
Considerations for future research:
- Considering the clinical importance of these findings, new research is needed to get better insight into the efficacy of micronutrient supplements in managing T2DM
- Selenium homeostasis, selenoprotein, insulin signaling/secretion, and carbohydrate/lipid metabolism are linked in multiple and complex ways but the authors could not explain why chromium supplementation would lower blood glucose more effectively than selenium supplementation, and suggest more research is needed to clarify this
- While vitamin K status could be an emerging treatment target in T2DM prevention and management, it remains to be determined whether vitamin K supplementation has an advantage over other nutrients in terms of hypoglycemic effect, and further research is necessary
- The beneficial effect of vitamin E and niacin supplements regarding lipid metabolism warrant investigation through more rigorous comparative studies.
Abstract
Medical nutrition treatment can manage diabetes and slow or prevent its complications. The comparative effects of micronutrient supplements, however, have not yet been well established. We aimed at evaluating the comparative effects of vitamin and mineral supplements on managing glycemic control and lipid metabolism for type 2 diabetes mellitus (T2DM) to inform clinical practice. Electronic and hand searches for randomized controlled trials (RCTs) were performed until June 1, 2022. We selected RCTs enrolling patients with T2DM who were treated with vitamin supplements, mineral supplements, or placebo/no treatment. Data were pooled via frequentist random-effects network meta-analyses. A total of 170 eligible trials and 14223 participants were included. Low to very low certainty evidence established chromium supplements as the most effective in reducing fasting blood glucose levels and homeostasis model assessment of insulin resistance (SUCRAs: 90.4% and 78.3%, respectively). Vitamin K supplements ranked best in reducing glycated hemoglobin A1c and fasting insulin levels (SUCRAs: 97.0% and 82.3%, respectively), with moderate to very low certainty evidence. Vanadium supplements ranked best in lowering total cholesterol levels with very low evidence certainty (SUCRAs:100%). Niacin supplements ranked best in triglyceride reductions and increasing high-density lipoprotein cholesterol levels with low to very low evidence certainty (SUCRAs:93.7% and 94.6%, respectively). Vitamin E supplements ranked best in reducing low-density lipoprotein cholesterol levels with very low evidence certainty (SUCRAs:80.0%). Our analyses indicated that micronutrient supplements, especially chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be more efficacious in managing T2DM than other micronutrients. Considering the clinical importance of these findings, new research is needed to get better insight into this issue.
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Age-Dependent Relationships Between Disease Risk and Testosterone Levels: Relevance to COVID-19 Disease.
Muehlenbein, M, Gassen, J, Nowak, T, Henderson, A, Morris, B, Weaver, S, Baker, E
American journal of men's health. 2023;17(2):15579883221130195
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A growing body of research finds that in men, testosterone levels may be prognostic of clinical outcomes related to coronavirus disease 2019 (COVID-19 disease). The presence of pre-existing chronic conditions in many patients with COVID-19 disease further complicates the relationship among testosterone and severe outcomes. The aim of this study was to examine whether pre-existing conditions for severe COVID-19 disease were related to serum-free testosterone levels in men who had not been infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. This study obtained data from men (n = 142) who participated in the longitudinal study Waco COVID Survey. All data included in the study was collected as part of the initial intake survey and first laboratory appointment. Results show that serum-free testosterone levels decreased as a function of age. In fact, greater burden of pre-existing conditions for severe COVID-19 disease was related to lower testosterone levels among men younger than 40 years of age. Furthermore, in men older than 40 years of age the decrease in testosterone that accompanies aging attenuated the effect of the clinical risk score on free testosterone levels. Authors conclude that their findings add important insights into the complex role of androgens in chronic and infectious diseases and contribute to the growing body of literature on the relationship between chronic disease and men’s testosterone levels.
Abstract
Testosterone levels in men appear to be prognostic of a number of disease outcomes, including severe COVID-19 disease. Testosterone levels naturally decline with age and are lower in individuals with a number of comorbidities and chronic conditions. Low testosterone may therefore be both a cause and a consequence of illness, including COVID-19 disease. The present project examines whether preexisting conditions for severe COVID-19 disease were themselves related to serum-free testosterone levels in men who had not been infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. A clinical risk score for severe COVID-19 disease was computed based on the results of previously published meta-analyses and cohort studies, and relationships between this score and testosterone levels were tested in 142 men ages 19 to 82 years. Greater burden of preexisting conditions for severe COVID-19 disease was related to lower testosterone levels among men younger than 40 years of age. In older men, the decrease in testosterone that accompanies aging attenuated the effect of the clinical risk score on free testosterone levels. Given that older age itself is a predictor of COVID-19 disease severity, these results together suggest that the presence of preexisting conditions may confound the relationship between testosterone levels and COVID-19 disease outcomes in men. Future research examining relationships among testosterone and outcomes related to infectious and chronic diseases should consider potential confounds, such as the role of preexisting conditions.
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Probiotics intervention in preventing conversion of impaired glucose tolerance to diabetes: The PPDP follow-on study.
Yan, Q, Hu, W, Tian, Y, Li, X, Yu, Y, Li, X, Feng, B
Frontiers in endocrinology. 2023;14:1113611
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Compared with normal glucose tolerance, people with prediabetes, especially impaired glucose tolerance (IGT), have a higher risk of developing type 2 diabetes mellitus (T2DM). Early intervention can significantly reduce the probability of developing T2DM in the IGT population. The aim of this study was to observe the effect of early probiotic intervention on the conversion of T2DM after 6 years. This study was a follow-on study of the Probiotics Prevention Diabetes Program (PPDP) Study. A total of 39 non-T2DM patients agreed to continue with the follow up of glucose metabolism for the following 4 years. Results showed that supplementation with active probiotics of Bifidobacterium, Lactobacillus acidophilus and Enterococcus faecalis is safe, although it does not reduce the risk of IGT conversion to diabetes mellitus. Authors conclude that more clinical and laboratory studies using large samples and long-term observation are needed to explore the effects of different probiotic strains on IGT.
Abstract
OBJECTIVES The purpose of this study was to assess the incidence of type 2 diabetes mellitus (T2DM) after 6 years in patients with IGT who received early probiotic intervention in the Probiotics Prevention Diabetes Program (PPDP) trial. METHODS 77 patients with IGT in the PPDP trial were randomized to either probiotic or placebo. After the completion of the trial, 39 non-T2DM patients were invited to follow up glucose metabolism after the next 4 years. The incidence of T2DM in each group was assessed using Kaplan-Meier analysis. The 16S rDNA sequencing technology was used to analyze gut microbiota's structural composition and abundance changes between the groups. RESULTS The cumulative incidence of T2DM was 59.1% with probiotic treatment versus 54.5% with placebo within 6 years, there was no significant difference in the risk of developing T2DM between the two groups (P=0.674). CONCLUSIONS Supplemental probiotic therapy does not reduce the risk of IGT conversion to T2DM. CLINICAL TRIAL REGISTRATION https://www.chictr.org.cn/showproj.aspx?proj=5543, identifier ChiCTR-TRC-13004024.
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Is Extra Virgin Olive Oil the Critical Ingredient Driving the Health Benefits of a Mediterranean Diet? A Narrative Review.
Flynn, MM, Tierney, A, Itsiopoulos, C
Nutrients. 2023;15(13)
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Cardiovascular diseases (CVDs) are the largest contributor to deaths globally, followed by cancers, chronic respiratory diseases and diabetes. It is estimated that 90% of deaths from CVD can be prevented with modifiable risk factors such as diet. The Mediterranean diet, which is rich in extra virgin olive oil (EVOO), is important in the prevention of chronic diseases. There is however very little focus on differentiating healthy fats such as EVOO from other fats and oils in dietary guidelines. This review of 34 studies aims to compare the effect of diets that include EVOO on cardiometabolic risk factors for heart disease, metabolic syndrome, and type 2 diabetes. It looks at the effects on blood pressure (SBP), low- and high-density lipoprotein cholesterol, (HDP-c and LDD-c) fasting blood glucose (FBG) and body weight. It also assesses from published studies the minimum daily amount of EVOO and the shortest time needed to see improvements in the risk factors. There is evidence to support EVOO in improving SBP in patients with high blood pressure, with studies suggesting that specific phenols in the oil may be important compared with a refined olive oil. Compared with other dietary fats or low-fat diets, EVOO can decrease LDL-c and increase HDL-c. Diets including daily EVOO are effective for weight loss. The effect of EVOO on FBG compared with other diets is not yet clear. The authors state that EVOO would be a far superior choice compared with other dietary fats, low-fat diets, or refined olive oil. The daily use of EVOO starting at approximately two tablespoons a day will improve a range of risk factors in as few as three weeks.
Abstract
Most chronic diseases are preventable with a healthy diet, although there is debate about the optimal dietary approach. Increasingly more countries are focusing on food-based guidelines rather than the traditional nutrient-based approach. Although there is good agreement on plant foods, controversy remains about the types and amounts of fats and oils. This narrative review aims to systematically summarize and evaluate the latest evidence on the protective effects of extra virgin olive oil (EVOO) on disease risk factors. A systematic search of the relevant literature using PubMed, Cochrane Library, and Embase databases was conducted for the years 2000 through December 2022. A narrative synthesis was then undertaken. Of 281 retrieved articles, 34 articles fulfilled our inclusion criteria and were included. Compared with other dietary fats and low-fat diets, EVOO is superior in the management of clinical biomarkers including lowering blood pressure and LDL-c, increasing protective HDL-c, improving glycemic control, and weight management. The protective effects of EVOO are likely due to its polyphenol content rather than the monounsaturated fat content. It is therefore important to promote the regular use of EVOO in the context of healthy dietary patterns such as the Mediterranean diet for maximal health benefit.
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The entero-endocrine response following a mixed-meal tolerance test with a non-nutritive pre-load in participants with pre-diabetes and type 2 diabetes: A crossover randomized controlled trial proof of concept study.
Muilwijk, M, Beulens, JWJ, Groeneveld, L, Rutters, F, Blom, MT, Agamennone, V, van den Broek, T, Keijser, BJF, Hoevenaars, F
PloS one. 2023;18(8):e0290261
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There is a process within the mouth and gut that is responsible for sensing nutrients and releasing hormones, which is called the entero-endocrine response. This response is responsible for ensuring that we do not overeat and maintain normal metabolism. The use of stevia, which is a sweetener, instead of sugar in food has been reported to have blood sugar lowering effects, which may be of benefit to individuals with type 2 diabetes (T2D). However, it is not fully understood how stevia can affect the entero-endocrine response, especially in individuals with T2D and prediabetes. This cross-over randomised control trial aimed to determine the entero-endocrine response in 20 individuals with either T2D or prediabetes following the consumption of stevia before a meal. The results showed that there was an enhanced entero-endocrine response to stevia in individuals with T2D compared to those with prediabetes. Blood sugar and the hormones responsible for lowering blood sugar and appetite suppression were all higher in individuals with T2D. There were no associations between the composition of the oral or gut microbiota and the entero-endocrine response. It was concluded that the consumption of stevia before a meal differentially effects the entero-endocrine response in individuals with T2D and prediabetes. This study could be used by healthcare professionals to understand that the consumption of stevia before a meal elicits an individual response. However, as this was a small study, further understanding of the mechanisms involved would be of benefit.
Abstract
INTRODUCTION This crossover randomized controlled trial (RCT) investigated differences in short-term entero-endocrine response to a mixed-meal tolerance test preceded by nutrient sensing between participants with pre-diabetes (pre-T2D) and type 2 diabetes (T2D). Additionally, differences in gut and oral microbiome composition between participants with a high and low entero-endocrine response were investigated. RESEARCH DESIGN AND METHODS Ten participants with pre-T2D and ten with T2D underwent three test days with pre-loads consisting of either swallowing water (control), or rinsing with a non-nutritive sweetener solution, or swallowing the sweetener solution before a mixed-meal tolerance test. Blood glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, glucose, insulin and peptide YY (PYY) were determined at t = -20, 0, 15, 30, 60, 120 and 240 minutes. The composition of the oral and gut microbiome at baseline were also determined. RESULTS The entero-endocrine response differed by pre-loads, e.g. a lower PYY response after swallowing the non-nutritive sweetener (-3585.2pg/mL [95% CI: -6440.6; -729.8]; p = 0.01). But it also differed by T2D status, e.g. a higher glucose, glucagon and PYY response was found in participants with T2D, compared to those with pre-T2D. Evidence for associations between the oral and gut microbiome composition and the entero-endocrine response was limited. Still, the level of entero-endocrine response was associated with several oral microbiome measures. Higher oral anterior α-diversity was associated with a lower PYY response (e.g. Inverse Simpson index -1357pg/mL [95% CI -2378; -336; 1.24]), and higher oral posterior α-diversitywith a higher GIP response (e.g. Inverse Simpson index 6773pg/mL [95% CI 132; 13414]) in models adjusted for sex, age and T2D status. CONCLUSIONS Non-nutritive pre-loads influence the entero-endocrine response to a mixed-meal, and this effect varies based on (pre-)T2D status. The entero-endocrine response is likely not associated with the gut microbiome, and there is limited evidence for association with the α-diversity of the oral microbiome composition. TRIAL REGISTRATION Trial register: Netherlands Trial Register NTR7212, accessible through International Clinical Trials Registry Platform: ICTRP Search Portal (who.int).
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Gut microbiota modulate distal symmetric polyneuropathy in patients with diabetes.
Yang, J, Yang, X, Wu, G, Huang, F, Shi, X, Wei, W, Zhang, Y, Zhang, H, Cheng, L, Yu, L, et al
Cell metabolism. 2023;35(9):1548-1562.e7
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Distal symmetric polyneuropathy (DSPN) is the most common complication associated with diabetes, which can lead to pain, numbness, and weakness or tingling in the limbs or parts of the body. There are no cures for DSPN only drugs to manage symptoms, highlighting a need for further research. Recently it has been shown that the gut microbiota of individuals with DSPN differs to that of healthy individuals, but it is unclear as to the significance of this. This randomised control trial aimed to determine the effect of transplanting faecal microbiota from healthy individuals into those with DSPN. The results showed that DSPN was associated with a decreased abundance of beneficial gut bacteria and an increased abundance of pathogenic bacteria. Furthermore, compared to placebo, DSPN was alleviated in all 22 patients who received a faecal microbiota transplant from healthy subjects. There was an increase in gut microbiota associated with the production of beneficial short chain fatty acids and a decrease in toxin production. It was concluded that dysbiosis in the gut microbiota contributes to DSPN, which can be alleviated by faecal microbial transplant from healthy individuals. This study could be used by healthcare professionals to understand that the gut microbiota has an important role in DSPN. Further larger studies would be warranted before recommending faecal microbial transplant to individuals with this disorder.
Abstract
The pathogenic mechanisms underlying distal symmetric polyneuropathy (DSPN), a common neuropathy in patients with diabetes mellitus (DM), are not fully understood. Here, we discover that the gut microbiota from patients with DSPN can induce a phenotype exhibiting more severe peripheral neuropathy in db/db mice. In a randomized, double-blind, and placebo-controlled trial (ChiCTR1800017257), compared to 10 patients who received placebo, DSPN was significantly alleviated in the 22 patients who received fecal microbiota transplants from healthy donors, independent of glycemic control. The gut bacterial genomes that correlated with the Toronto Clinical Scoring System (TCSS) score were organized in two competing guilds. Increased guild 1, which had higher capacity in butyrate production, and decreased guild 2, which harbored more genes in synthetic pathway of endotoxin, were associated with improved gut barrier integrity and decreased proinflammatory cytokine levels. Moreover, matched enterotype between transplants and recipients showed better therapeutic efficacy with more enriched guild 1 and suppressed guild 2. Thus, changes in these two competing guilds may play a causative role in DSPN and have the potential for therapeutic targeting.
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High-fiber diet ameliorates gut microbiota, serum metabolism and emotional mood in type 2 diabetes patients.
Chen, L, Liu, B, Ren, L, Du, H, Fei, C, Qian, C, Li, B, Zhang, R, Liu, H, Li, Z, et al
Frontiers in cellular and infection microbiology. 2023;13:1069954
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Accumulating studies have demonstrated that there are strong correlations between type 2 diabetes mellitus (T2DM) and gut microbiota. A nutritious diet composed of an adequate level of dietary fibres could provide enough carbohydrates for the gut microbiota to ferment, and the microbial metabolites could provide energy supply and regulate the immune function of the host. The aim of this study was to analyse the changes in gut microbiota, serum metabolism and emotional mood of patients with T2DM after consumption of a high-fibre diet. This study was a randomised, open-label, parallel-group clinical trial in T2DM patients with a 4-week treatment period. Seventeen patients clinically diagnosed with T2DM enrolled in the clinical trial and were randomly assigned into two groups: the control group (n = 8) or the intervention group (n = 9). Results showed that the high-fibre diet (compared to the control group): - improved glucose homeostasis and lipid metabolism of participants with T2DM; - decreased serum levels of inflammatory chemokines in participants with T2DM; - alleviated depression and anxiety symptoms, particularly by the uptake of more diverse carbohydrates in the diet in participants with T2DM; - enhanced the diversity of gut microbiota in the treatment group. Authors conclude that the dietary source of fibre demonstrated protective impacts on the gut ecosystem, and the alteration of the gut microbiota composition improved the glucose homeostasis in patients with T2DM.
Abstract
Previous studies have demonstrated that patients with type 2 diabetes mellitus (T2DM) often had the problems of fecal microbiota dysbiosis, and were usually accompanied with psychiatric comorbidities (such as depression and anxiety). Here, we conducted a randomized clinical study to analyze the changes in gut microbiota, serum metabolism and emotional mood of patients with T2DM after consumption of a high-fiber diet. The glucose homeostasis of participants with T2DM was improved by the high-fiber diet, and the serum metabolome, systemic inflammation and psychiatric comorbidities were also altered. The increased abundances of Lactobacillus, Bifidobacterium and Akkermansias revealed that the proportions of beneficial gut microbes were enriched by the high-fiber diet, while the abundances of Desulfovibrio, Klebsiella and other opportunistic pathogens were decreased. Therefore, the current study demonstrated that the intestinal microbiota alterations which were influenced by the high-fiber diet could improve the serum metabolism and emotional mood of patients with T2DM.
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Sleep-Opt-In: A Randomized Controlled Pilot Study to Improve Sleep and Glycemic Variability in Adults With Type 1 Diabetes.
Martyn-Nemeth, P, Duffecy, J, Quinn, L, Steffen, A, Baron, K, Chapagai, S, Burke, L, Reutrakul, S
The science of diabetes self-management and care. 2023;49(1):11-22
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Insufficient sleep (insufficient total sleep time) and irregular sleep timing (variability in the occurrence of sleep within a 24-hour period) are increasingly recognized as important contributors to glycaemic control and variability in type 1 diabetes (T1D). The aims of this study were to evaluate the feasibility and acceptability of a sleep intervention (Sleep-Opt-In) targeted for adults with type 1 diabetes with short or irregular sleep and to examine the effects of Sleep-Opt-In on sleep duration and regularity, glucose indices, and patient-reported outcomes. This study was a randomised controlled parallel trial design. Participants (n=14) were randomly assigned to either the Sleep-Opt-In intervention or a Healthy Living attention control group. Results showed that: - Sleep-Opt-In was feasible and acceptable to the target population. - participants with objectively confirmed short or irregular sleep, sleep irregularity improved by 25 minutes on average, whereas sleep duration improved only negligibly (8 minutes). - the control group experienced an increase in sleep duration but no change in sleep regularity. Authors conclude that Sleep-Opt-In is feasible, acceptable, and promising for further evaluation to improve sleep duration or regularity, glucose parameters and important patient reported outcomes of diabetes distress, daytime sleepiness, fatigue and depressive mood in the T1D population.
Abstract
PURPOSE The purpose of this study was to evaluate the feasibility and acceptability of a technology-assisted behavioral sleep intervention (Sleep-Opt-In) and to examine the effects of Sleep-Opt-In on sleep duration and regularity, glucose indices, and patient-reported outcomes. Short sleep duration and irregular sleep schedules are associated with reduced glycemic control and greater glycemic variability. METHODS A randomized controlled parallel-arm pilot study was employed. Adults with type 1 diabetes (n = 14) were recruited from the Midwest and randomized 3:2 to the sleep-optimization (Sleep-Opt-In) or Healthy Living attention control group. Sleep-Opt-In was an 8-week, remotely delivered intervention consisting of digital lessons, sleep tracker, and weekly coaching phone calls by a trained sleep coach. Assessments of sleep (actigraphy), glucose (A1C, continuous glucose monitoring), and patient-reported outcomes (questionnaires for daytime sleepiness, fatigue, diabetes distress, and depressive mood) were completed at baseline and at completion of the intervention. RESULTS Sleep-Opt-In was feasible and acceptable. Those in Sleep-Opt-In with objectively confirmed short or irregular sleep demonstrated an improvement in sleep regularity (25 minutes), reduced glycemic variability (3.2%), and improved time in range (6.9%) compared to the Healthy Living attention control group. Patient-reported outcomes improved only for the Sleep-Opt-In group. Fatigue and depressive mood improved compared to the control. CONCLUSIONS Sleep-Opt-In is feasible, acceptable, and promising for further evaluation as a means to improve sleep duration or regularity in the population of people with type 1 diabetes.
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Effect of aerobic exercise, slow deep breathing and mindfulness meditation on cortisol and glucose levels in women with type 2 diabetes mellitus: a randomized controlled trial.
Obaya, HE, Abdeen, HA, Salem, AA, Shehata, MA, Aldhahi, MI, Muka, T, Marques-Sule, E, Taha, MM, Gaber, M, Atef, H
Frontiers in physiology. 2023;14:1186546
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Stress is considered to be an important factor in type 2 diabetes mellitus (T2DM) and aerobic exercise can help modulate the stress response as well as being important in the management of diabetes. Mindfulness meditation and deep breathing have also been shown to have positive effects on both stress and T2DM. This 6-week single-blind, randomised, controlled trial evaluated the effect of 10 min slow deep breathing and 10 min mindfulness meditation following a 40 min aerobic exercise programme, compared to the 40 min aerobic exercise alone, on fasting blood glucose (FBG) and cortisol levels in 58 stressed women with T2DM. FBG and cortisol levels improved in both groups but more so in the group who received the deep breathing and mindfulness meditation in addition to the exercise intervention: 20% vs 30% reduction in cortisol and 10% vs 15% reduction in FBG. The authors conclude that adding slow deep breathing and mindfulness meditation to an exercise programme may be useful in the management of stressed women with T2DM and reduce their cardiometabolic risk.
Expert Review
Conflicts of interest:
None
Take Home Message:
Practitioners could consider slow deep breathing and mindfulness meditation, added to aerobic exercise, as potentially useful components of the T2DM management program for stressed women.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
Stress, a key factor for Type 2 diabetes mellitus (T2DM), stimulates the hypothalamus-pituitary-adrenal gland (HPA) and triggers parasympathetic nerve withdrawal, leading to increased circulating cortisol levels and higher levels of blood glucose. Exercise is a key intervention that can modulate the HPA axis and help manage stress.
Methods
Fifty-eight women (aged between 40-50), diagnosed with T2DM for at least 5 years but medically stable with moderate to high stress scores were randomised to either aerobic training (AT) or aerobic exercise combined with slow deep breathing and mindfulness meditation (DMM) training three times weekly over 6-weeks.
AT group performed aerobic exercise on a treadmill at an intensity of 60%– 75% of the maximum heart rate for a total of 40 min, including a 5 minute warm up and 5 min cool down.
AT + DMM group performed a combination of aerobic exercise as per the AT group followed by a total of 10 minutes of diaphragmatic slow, deep breathing; and mindfulness meditation.
Results
Both groups showed a change from baseline in serum cortisol to p<0.0001
At 6 weeks in the AT + DMM group, the primary outcome of serum cortisol (nmol/L) levels was 12.59 nmol/L [95% CI 4.45-6.52] a decrease of 30.29% and the fasting blood glucose levels (secondary outcome) was 136.37mg/dl (95% CI: 9.19–2.6) a decrease of 14.54%
In the AT group performing only aerobic exercise decreased serum cortisol levels by 20.16% and FBG levels decreased by 9.97%.
Conclusion
This study showed that combining slow deep breathing and mindfulness meditation with aerobic exercise reduced the serum cortisol (p = 0.01) and FBG levels (p = 0.001) in women with T2DM compared to when only aerobic training was performed.
Clinical practice applications:
Consider a combined therapy approach with diaphragmatic breathing exercises and aerobic exercises that targets both the endocrine and autonomic nervous systems, as this may have a synergistic effect to assist with maintaining normal blood sugar levels and cortisol levels in individuals with T2DM.
Considerations for future research:
Future research is needed to determine the most effective combination of therapies for managing both FBG and serum cortisol levels in individuals with T2DM.
Abstract
Background: Aerobic exercise combined with breathing exercise can be an integral part of diabetes mellitus treatment. This single-center, randomized, parallel-group study investigated the effect of the combination of aerobic exercise with slow deep breathing and mindfulness meditation on the glucose and cortisol levels of women with type 2 diabetes mellitus (T2DM). Materials and Methods: Fifty-eight middle-aged women with T2DM (mean age: 45.67 ± 2.92 years) were randomly assigned to either the aerobic training group (AT: n = 29; mean age [46.1 ± 2.7 years]) or the aerobic exercise combined with slow deep breathing and mindfulness meditation (AT + DMM: n = 29; mean age [45.24 ± 3.14 years]). Aerobic exercise was performed at 60%-75% of the maximum heart rate. The women in each group were asked to perform the training three times weekly over a 6-week period. The duration of each session was 40 min for the AT group and 60 min for the AT + DMM group. The two groups were asked to perform aerobic exercise at 60%-75% of the maximum heart rate. Their fasting blood glucose (FBG) and serum cortisol levels were measured at the baseline and after the 6 weeks. Results: Compared with the AT group, the group undertaking 6 weeks of aerobic training combined with slow, deep breathing exercises and mindfulness meditation showed significantly lower levels of FBG (p = 0.001) and cortisol levels (p = 0.01) than the AT group. Conclusion: The addition of slow deep breathing and mindfulness meditation to aerobic exercise can better control the glucose and cortisol levels of women with T2DM and thereby improve their outcomes and decrease their cardiometabolic risk.