• Bawazir A
• Patel V

• Diabetes Mellitus, Type 2
• Diet, Carbohydrate-Restricted
• Glycemic Control
• Hyperlipidemias
• Obesity

Abstract: Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by elevated blood glucose levels. Nutritional therapy is an essential part in managing T2DM and often a high-carbohydrate low-calorie diet is advised. Some clinicians and researchers recommend low-carbohydrate diets (LCDs) as the first-line therapy in managing T2DM but this dietary approach is controversial. The aim of this article is to clarify the evidence of the effect of LCDs on glycemic control, weight loss, and blood lipids biomarkers in T2DM patients based on recent randomized controlled trials (RCTs).

Methods: The electronic databases of Pubmed, Embase, Web of Science, and Cochrane Library were searched for recent LCDs studies conducted in adults with T2Dm. The search was restricted to human rCTs that were published in English between 2015 and July, 2019, and compared LCDs with higher carbohydrate diets. The primary outcomes were changes in glycated hemoglobin, body weight, and blood lipids concentrations.

Results: Nine trials met the criteria and included in this article. The sample sizes ranged from 25 to 115 adults with study duration from 3 months to 2 years. Six trials showed a significant reduction in glycated hemoglobin (hbA1C) in the LCDs groups compared with the trial control group while other trials showed similar improvements in both groups. The reductions of hbA1C in the LCDs groups were from -0.5% to -1.34% (approximates to 5 to 14 mmol/mol). The variation of hbA1C reduction seems to be correlated with the levels of restricted carbohydrate in the intervention groups. It appears that there is no association between the length of study duration and the hbA1C improvement. Statistically significant triglyceride reduction and weight loss in the LCDs groups compared with the control groups were reported in five studies with similar improvements in other trials. Greater or comparable improvements were observed in blood concentrations of high density lipoprotein cholesterol, low density lipoprotein cholesterol, and total cholesterol in the LCDs groups. LCDs achieved better or similar dropout rates and reductions of diabetes medications with T2DM.

Conclusion: There is evidence that LCDs are effective in improving glycemic control, weight loss, and blood lipids biomarkers in individuals with T2Dm. Large samples and long-duration studies maybe needed to confirm these findings and to establish a therapeutic low-carbohydrate diet for patients with T2Dm and change existing guidelines.

Author keywords: Type 2 Diabetes mellitus, Low carbohydrate diets, glycemic control, Weight loss, Triglycerides, high density lipoprotein cholesterol

This abstract is reproduced with the permission of the publisher.