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1.
The Emerging Role of Polyphenols in the Management of Type 2 Diabetes.
Wang, Y, Alkhalidy, H, Liu, D
Molecules (Basel, Switzerland). 2021;(3)
Abstract
Type 2 diabetes (T2D) is a fast-increasing health problem globally, and it results from insulin resistance and pancreatic β-cell dysfunction. The gastrointestinal (GI) tract is recognized as one of the major regulatory organs of glucose homeostasis that involves multiple gut hormones and microbiota. Notably, the incretin hormone glucagon-like peptide-1 (GLP-1) secreted from enteroendocrine L-cells plays a pivotal role in maintaining glucose homeostasis via eliciting pleiotropic effects, which are largely mediated via its receptor. Thus, targeting the GLP-1 signaling system is a highly attractive therapeutic strategy to treatment T2D. Polyphenols, the secondary metabolites from plants, have drawn considerable attention because of their numerous health benefits, including potential anti-diabetic effects. Although the major targets and locations for the polyphenolic compounds to exert the anti-diabetic action are still unclear, the first organ that is exposed to these compounds is the GI tract in which polyphenols could modulate enzymes and hormones. Indeed, emerging evidence has shown that polyphenols can stimulate GLP-1 secretion, indicating that these natural compounds might exert metabolic action at least partially mediated by GLP-1. This review provides an overview of nutritional regulation of GLP-1 secretion and summarizes recent studies on the roles of polyphenols in GLP-1 secretion and degradation as it relates to metabolic homeostasis. In addition, the effects of polyphenols on microbiota and microbial metabolites that could indirectly modulate GLP-1 secretion are also discussed.
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2.
Fixed-Ratio Combinations of Basal Insulin and GLP-1RA in the Management of Type 2 Diabetes Mellitus: Highlights from the Literature.
Lisco, G, De Tullio, A, Guastamacchia, E, Triggiani, V
Endocrine, metabolic & immune disorders drug targets. 2021;(4):626-646
Abstract
New pieces of evidence suggest that combining basal insulin with glucagone-like peptide 1 receptor agonists (GLP-1RA) in patients with type 2 diabetes could promptly ameliorate glucose control and prevent both hypoglycemic events and unnecessary weight gain compared to more intensive insulin regimens. To review the efficacy/effectiveness and safety of fixed-ratio combinations of basal insulin and GLP- 1RA (FRCs). Authors searched PubMed/MEDLINE, ClinicalTrials.gov, Cochrane Library, and Google Scholar for freely available original articles, randomized clinical trials (RCTs), clinical reviews, and meta-analysis written in English until January 2020. FRCs provide significative reductions in HbA1c levels in both insulin-naïve (-1.4% to -2%) and insulin- experienced (-1.5% to -2%) type 2 diabetic patients with moderate glucose impairment. More patients achieved the recommended glycemic targets on FRCs compared to those on mono-therapy with basal insulin or GLP-1RAs. The intensification with FRCs results in better glycemic control compared to basal insulin at fasting as well as during the postprandial state. The frequency of hypoglycemia is similar or lower in patients treated with FRCs than in those on basal insulin alone at a similar dose. Weight trend can be variable, ranging from -2.7 to +2 Kg for iDegLira and -0.7 to -1.3 Kg for iGlar- Lixi. However, a lower weight gain is obtained with iDegLira compared to iDeg (-2.2 to -2.5 Kg), iGlar (-1.7 to -3.2 Kg), and basal-bolus (-3.6 Kg) as well as with iGlarLixi compared to iGlar (-1.4 Kg). FRCs should be considered to safely improve the metabolic control in type 2 diabetic patients with moderate glycemic impairment while on oral medications, basal oral regimen or GLP-1RAs. However, a few but significative pieces of evidence suggest that FRCs could be a safe and effective treatment instead of a low dose basal-bolus intensification for patients with mild or moderate glucose impairment in order to reduce the risk of hypoglycemia and unnecessary weight gain, and for simplifying treatment regimen as well.
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3.
The many actions of insulin in skeletal muscle, the paramount tissue determining glycemia.
Sylow, L, Tokarz, VL, Richter, EA, Klip, A
Cell metabolism. 2021;(4):758-780
Abstract
As the principal tissue for insulin-stimulated glucose disposal, skeletal muscle is a primary driver of whole-body glycemic control. Skeletal muscle also uniquely responds to muscle contraction or exercise with increased sensitivity to subsequent insulin stimulation. Insulin's dominating control of glucose metabolism is orchestrated by complex and highly regulated signaling cascades that elicit diverse and unique effects on skeletal muscle. We discuss the discoveries that have led to our current understanding of how insulin promotes glucose uptake in muscle. We also touch upon insulin access to muscle, and insulin signaling toward glycogen, lipid, and protein metabolism. We draw from human and rodent studies in vivo, isolated muscle preparations, and muscle cell cultures to home in on the molecular, biophysical, and structural elements mediating these responses. Finally, we offer some perspective on molecular defects that potentially underlie the failure of muscle to take up glucose efficiently during obesity and type 2 diabetes.
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4.
Current Aspects of the Role of Autoantibodies Directed Against Appetite-Regulating Hormones and the Gut Microbiome in Eating Disorders.
Smitka, K, Prochazkova, P, Roubalova, R, Dvorak, J, Papezova, H, Hill, M, Pokorny, J, Kittnar, O, Bilej, M, Tlaskalova-Hogenova, H
Frontiers in endocrinology. 2021;:613983
Abstract
The equilibrium and reciprocal actions among appetite-stimulating (orexigenic) and appetite-suppressing (anorexigenic) signals synthesized in the gut, brain, microbiome and adipose tissue (AT), seems to play a pivotal role in the regulation of food intake and feeding behavior, anxiety, and depression. A dysregulation of mechanisms controlling the energy balance may result in eating disorders such as anorexia nervosa (AN) and bulimia nervosa (BN). AN is a psychiatric disease defined by chronic self-induced extreme dietary restriction leading to an extremely low body weight and adiposity. BN is defined as out-of-control binge eating, which is compensated by self-induced vomiting, fasting, or excessive exercise. Certain gut microbiota-related compounds, like bacterial chaperone protein Escherichia coli caseinolytic protease B (ClpB) and food-derived antigens were recently described to trigger the production of autoantibodies cross-reacting with appetite-regulating hormones and neurotransmitters. Gut microbiome may be a potential manipulator for AT and energy homeostasis. Thus, the regulation of appetite, emotion, mood, and nutritional status is also under the control of neuroimmunoendocrine mechanisms by secretion of autoantibodies directed against neuropeptides, neuroactive metabolites, and peptides. In AN and BN, altered cholinergic, dopaminergic, adrenergic, and serotonergic relays may lead to abnormal AT, gut, and brain hormone secretion. The present review summarizes updated knowledge regarding the gut dysbiosis, gut-barrier permeability, short-chain fatty acids (SCFA), fecal microbial transplantation (FMT), blood-brain barrier permeability, and autoantibodies within the ghrelin and melanocortin systems in eating disorders. We expect that the new knowledge may be used for the development of a novel preventive and therapeutic approach for treatment of AN and BN.
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5.
Effects of interrupting prolonged sitting on postprandial glycemia and insulin responses: A network meta-analysis.
Quan, M, Xun, P, Wu, H, Wang, J, Cheng, W, Cao, M, Zhou, T, Huang, T, Gao, Z, Chen, P
Journal of sport and health science. 2021;(4):419-429
Abstract
PURPOSE This study aimed to evaluate the effectiveness of physical activity (PA) interrupting prolonged sitting (PS) on postprandial glycemia and insulin responses among adults. METHODS PubMed, EMBASE, Cochrane Library, Web of Science, CINAHL, PsycINFO, and the China National Knowledge Infrastructure databases were searched through September 30, 2020. Randomized controlled trials (RCTs) that examined the effect of all forms of PA interrupting PS on postprandial glycemia and/or insulin responses among adults without chronic diseases were included in this study. The risk of bias of included studies was evaluated based on the Cochrane tool. A network meta-analysis was performed to estimate the summary standardized mean differences (SMDs) with 95% confidence intervals (95%CIs) with random effects. RESULTS Thirty crossover RCTs were included in our review. These RCTs included 9 types of interventions that interrupted PS. When compared to PS by itself, light-intensity PA intermittent interrupting (LPA-INT) PS and moderate-intensity PA intermittent interrupting (MPA-INT) PS significantly lowered postprandial glycemia (SMD = -0.46, 95%CI: -0.70 to -0.21; SMD = -0.69, 95%CI: -1.00 to -0.37, respectively) and significantly reduced postprandial insulin response (SMD = -0.46, 95%CI: -0.66 to -0.26; SMD = -0.47, 95%CI: -0.77 to -0.17, respectively). Results of the clustered ranking plot indicated that MPA-INT was the most effective intervention in lowering postprandial glycemia and insulin responses. CONCLUSION Replacing PS with MPA-INT or LPA-INT has a positive effect in reducing postprandial glycemia and insulin responses, with MPA-INT being the optimal intervention strategy.
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6.
The use of D-chiro-Inositol in clinical practice.
Gambioli, R, Forte, G, Aragona, C, Bevilacqua, A, Bizzarri, M, Unfer, V
European review for medical and pharmacological sciences. 2021;(1):438-446
Abstract
OBJECTIVE D-chiro-Inositol has been widely used in clinical practice to induce ovulation in women with polycystic ovary syndrome. Only recent evidence established that this molecule acts through two different mechanisms, with potentially different outcomes. On the one hand, under a metabolic perspective, D-chiro-Inositol improves insulin signaling, thus restoring physiological insulin levels in resistant subjects. On the other hand, at a cellular level, it downregulates the expression of steroidogenic enzyme aromatase, which is responsible for the conversion of androgens to estrogens. MATERIALS AND METHODS We reviewed current literature in different databases, searching for D-chiro-Inositol in relation with one of the following keywords: myo-inositol, PCOS, infertility, insulin resistance, aromatase, androgen and inositol, testosterone, estrogen and inositol, estradiol, hypogonadotropic hypogonadism, fat tissue, estrogens and cancer, anovulation, uterine myoma, endometriosis, endometrial hyperplasia. RESULTS D-Chiro-Inositol treatment may be helpful in restoring physiological hormonal levels in various clinical disorders. However, D-Chiro-Inositol intervention should be carefully designed to avoid possible undesired side effects stemming from its multiple mechanisms of action. CONCLUSIONS We evaluated the optimal D Chiro-Inositol administration for different pathologies, defining dosages and timing. Even though further studies are required to validate our preliminary results, this paper is primarily intended to guide researchers through some of the pathways of D-Chiro-Inositol.
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7.
Carbohydrate restriction for diabetes: rediscovering centuries-old wisdom.
Lennerz, BS, Koutnik, AP, Azova, S, Wolfsdorf, JI, Ludwig, DS
The Journal of clinical investigation. 2021;(1)
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Free full text
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Abstract
Carbohydrate restriction, used since the 1700s to prolong survival in people with diabetes, fell out of favor after the discovery of insulin. Despite costly pharmacological and technological developments in the last few decades, current therapies do not achieve optimal outcomes, and most people with diabetes remain at high risk for micro- and macrovascular complications. Recently, low-carbohydrate diets have regained popularity, with preliminary evidence of benefit for body weight, postprandial hyperglycemia, hyperinsulinemia, and other cardiometabolic risk factors in type 2 diabetes and, with more limited data, in type 1 diabetes. High-quality, long-term trials are needed to assess safety concerns and determine whether this old dietary approach might help people with diabetes attain clinical targets more effectively, and at a lower cost, than conventional treatment.
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8.
Intranasal insulin.
Hallschmid, M
Journal of neuroendocrinology. 2021;(4):e12934
Abstract
The intranasal (IN) route enables the delivery of insulin to the central nervous system in the relative absence of systemic uptake and related peripheral side effects. Intranasally administered insulin is assumed to travel along olfactory and adjacent pathways and has been shown to rapidly accumulate in cerebrospinal fluid, indicating efficient transport to the brain. Two decades of studies in healthy humans and patients have demonstrated that IN insulin exerts functional effects on metabolism, such as reductions in food intake and body weight and improvements of glucose homeostasis, as well as cognition, ie, enhancements of memory performance both in healthy individuals and patients with mild cognitive impairment or Alzheimer's disease; these studies moreover indicate a favourable safety profile of the acute and repeated use of IN insulin. Emerging findings suggest that IN insulin also modulates neuroendocrine activity, sleep-related mechanisms, sensory perception and mood. Some, but not all studies point to sex differences in the response to IN insulin that need to be further investigated along with the impact of age. "Brain insulin resistance" is an evolving concept that posits impairments in central nervous insulin signalling as a pathophysiological factor in metabolic and cognitive disorders such as obesity, type 2 diabetes and Alzheimer's disease, and, notably, a target of interventions that rely on IN insulin. Still, the negative outcomes of longer-term IN insulin trials in individuals with obesity or Alzheimer's disease highlight the need for conceptual as well as methodological advances to translate the promising results of proof-of-concept experiments and pilot clinical trials into the successful clinical application of IN insulin.
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9.
Could Exogenous Insulin Ameliorate the Metabolic Dysfunction Induced by Glucocorticoids and COVID-19?
Whyte, MB, Vas, PRJ, Umpleby, AM
Frontiers in endocrinology. 2021;:649405
Abstract
The finding that high-dose dexamethasone improves survival in those requiring critical care due to COVID-19 will mean much greater usage of glucocorticoids in the subsequent waves of coronavirus infection. Furthermore, the consistent finding of adverse outcomes from COVID-19 in individuals with obesity, hypertension and diabetes has focussed attention on the metabolic dysfunction that may arise with critical illness. The SARS coronavirus itself may promote relative insulin deficiency, ketogenesis and hyperglycaemia in susceptible individuals. In conjunction with prolonged critical care, these components will promote a catabolic state. Insulin infusion is the mainstay of therapy for treatment of hyperglycaemia in acute illness but what is the effect of insulin on the admixture of glucocorticoids and COVID-19? This article reviews the evidence for the effect of insulin on clinical outcomes and intermediary metabolism in critical illness.
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10.
Non-glucose modulators of insulin secretion in healthy humans: (dis)similarities between islet and in vivo studies.
Henquin, JC
Metabolism: clinical and experimental. 2021;:154821
Abstract
Optimal metabolic homeostasis requires precise temporal and quantitative control of insulin secretion. Both in vivo and in vitro studies have often focused on the regulation by glucose although many additional factors including other nutrients, neurotransmitters, hormones and drugs, modulate the secretory function of pancreatic β-cells. This review is based on the analysis of clinical investigations characterizing the effects of non-glucose modulators of insulin secretion in healthy subjects, and of experimental studies testing the same modulators in islets isolated from normal human donors. The aim was to determine whether the information gathered in vitro can reliably be translated to the in vivo situation. The comparison evidenced both convincing similarities and areas of discordance. The lack of coherence generally stems from the use of exceedingly high concentrations of test agents at too high or too low glucose concentrations in vitro, which casts doubts on the physiological relevance of a number of observations made in isolated islets. Future projects resorting to human islets should avoid extreme experimental conditions, such as oversized stimulations or inhibitions of β-cells, which are unlikely to throw light on normal insulin secretion and contribute to the elucidation of its defects.