Low-carbohydrate diets and type 2 diabetes treatment: a meta-analysis of randomized controlled trials

Aim: To assess whether LC diets are associated with long-term improvement in glycemic control and weight loss in people with T2DM, and their cardiovascular and renal safety. Methods: Meta-analysis of randomized controlled trials lasting more than 3 months, retrieved through extensive search on PubMed, Embase, ClinicalTrial.gov, Cochrane databases up to March 1st, comparing LC diets and balanced carbohydrate diets in people with T2DM. Results: We retrieved 37 trials, including 3301 patients. Average carbohydrate intake in LC diets was 36% of total energy. LC diets were associated with significant reduction of HbA1c at 3 months (MD − 0.17%, 95% CI − 0.27, − 0.07), no difference at 6 and 12 months, and significant increase at 24 months (MD 0.23%, 95% CI MD 0.02, 0.44). VLC diets were associated with significant HbA1c reduction at 3 and 6 months (MD − 0.43% − 0.60, − 0.26%, and MD − 0.40% 95% CI − 0.59, − 0.22, respectively), but not at 12 and 24 months. LC diets were associated with significant BMI reduction at 6 months (− 1.35 kg/m2 95% CI, − 2.18, − 0.52), but not at other time points. Only a minority of trials reported data on renal function, so renal safety could not be assessed. No significant differences in body weight, lipid profile, or blood pressure were found in the long term. Conclusion: LC diets may produce small short-term improvements in HbA1c and weight, which are not maintained in the long term. Data on their renal safety are insufficient.