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Effect of lifestyle intervention on HbA1c levels in overweight and obese adults with type 2 diabetes across ethnicities: A systematic review and meta-analysis of randomized controlled trials.
Yang, J, Xia, Y, Sun, Y, Guo, Y, Shi, Z, Cristina do Vale Moreira, N, Zuo, H, Hussain, A
Diabetes research and clinical practice. 2023;199:110662
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Weight loss can benefit overweight and obese patients with type 2 diabetes mellitus (T2DM) with regards to cardiovascular risk factors, including glycaemic control. This systematic review and meta-analysis of 30 randomised controlled trials, including 7850 patients, aimed to evaluate racial/ethnic differences in response to lifestyle interventions for weight loss on glycosylated haemoglobin (HbA1c, a measure of glycaemic control) in overweight or obese patients with T2DM. Lifestyle interventions were associated with statistically significant reductions in HbA1c in White and Asian, but not in Black/African or Hispanic populations, although the latter were based on only 2 and 3 small trials, respectively, and may have therefore lacked statistical power. Reductions in HbA1c were seen in studies which led to a weight loss of more than 5% as well as those less than 5%, with greater reductions being seen in the former group. The authors conclude that ethnic differences should be taken into account when considering lifestyle interventions for diabetes management.
Abstract
AIMS: Weight reduction is fundamental for the management and remission of diabetes. We aimed to assess ethnic differences in the effects of lifestyle weight-loss interventions on HbA1c levels in overweight or obese adults with type 2 diabetes mellitus (T2DM). METHODS We systematically searched PubMed/MEDLINE and Web of Science online databases up to 31 Dec 2022. Randomized controlled trials using lifestyle weight-loss interventions in overweight or obese adults with T2DM were selected. We performed subgroup analyses to explore the heterogeneity across different ethnicities (Asians, White/Caucasians, Black/Africans and Hispanics). A random effects model was applied to calculate weighted mean difference (WMD) with 95% confidence interval (CI). RESULTS Thirty studies including 7580 subjects from different ethnicities were identified according to the predefined inclusion and exclusion criteria. HbA1c levels were significantly reduced by lifestyle weight-loss intervention. Notably, a significantly beneficial effect on HbA1c was observed in White/Caucasians (WMD = -0.59, 95% CI: -0.90, -0.28, P < 0.001) and Asians (WMD = -0.48, 95% CI: -0.63, -0.33, P < 0.001), but not in the Black/African or Hispanic group (both P > 0.05). The findings remained essentially unchanged in the sensitivity analysis. CONCLUSIONS Lifestyle weight-loss interventions had distinct beneficial effects on HbA1c levels in different ethnic groups with T2DM, especially in Caucasians and Asians.
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Effects of low-carbohydrate diets versus low-fat diets on metabolic risk factors in overweight and obese adults: A meta-analysis of randomized controlled trials.
Lei, L, Huang, J, Zhang, L, Hong, Y, Hui, S, Yang, J
Frontiers in nutrition. 2022;9:935234
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Low carbohydrate diets (LCD) and Low-fat diets (LFD) have both been shown to aid weight loss, however comparisons of the two have shown inconsistent results. This systematic review and meta-analysis of 33 studies involving 3939 individuals aimed to compare the effects of LFD and LCD on metabolic risk factors and weight loss. The results showed that compared with LFD, individuals on LCD had a greater reduction in fat circulating around the body, blood pressure, weight, and a greater increase in good cholesterol in the short-term. However, individuals on LFD had a greater decrease in bad cholesterol. In the long-term the benefits were the same for both diets. It was concluded that in the short-term LCD and LFD may have specific effects on body morphology and chemistry however over longer periods of time the benefits are similar. This study could be used by healthcare professionals to understand that different diets should be recommended to achieve different outcomes.
Abstract
BACKGROUND AND AIMS Low-carbohydrate diets (LCD) and low-fat diets (LFD) have shown beneficial effects on the management of obesity. Epidemiological studies were conducted to compare the effects of the two diets. However, the results were not always consistent. This study aimed to conduct a meta-analysis to compare the long-term effects of LCD and LFD on metabolic risk factors and weight loss in overweight and obese adults. METHODS We performed a systematic literature search up to 30 March, 2022 in PubMed, EMBASE, and Cochrane Library. The meta-analysis compared the effects of LCD (carbohydrate intake ≤ 40%) with LFD (fat intake < 30%) on metabolic risk factors and weight loss for ≥6 months. Subgroup analyses were performed based on participant characteristics, dietary energy intake, and the proportions of carbohydrates. RESULTS 33 studies involving a total of 3,939 participants were included. Compared with participants on LFD, participants on LCD had a greater reduction in triglycerides (-0.14 mmol/L; 95% CI, -0.18 to -0.10 mmol/L), diastolic blood pressure (-0.87 mmHg; 95% CI, -1.41 to -0.32 mmHg), weight loss (-1.33 kg; 95% CI, -1.79 to -0.87 kg), and a greater increase in high-density lipoprotein cholesterol (0.07 mmol/L; 95% CI, 0.06 to 0.09 mmol/L) in 6-23 months. However, the decrease of total cholesterol (0.14 mmol/L; 95% CI, 0.07 to 0.20 mmol/L) and low-density lipoprotein cholesterol (0.10 mmol/L; 95% CI, 0.06 to 0.14 mmol/L) was more conducive to LFD in 6-23 months. There was no difference in benefits between the two diets after 24 months. Subgroup analyses showed no significant difference in the reduction of total cholesterol, low-density lipoprotein cholesterol, and blood pressure between the two diets in participants with diabetes, hypertension, or hyperlipidemia. CONCLUSION The results suggest that LCD and LFD may have specific effects on metabolic risk factors and weight loss in overweight and obese adults over 6 months. At 24 months, the effects on weight loss and improvement of metabolic risk factors were at least the same. These indicated that we might choose different diets to manage the overweight and obese subjects. However, the long-term clinical efficacy and effects of various sources of carbohydrates or fat in the two diets need to be studied in the future.