A systematic review and meta-analysis was undertaken to determine the efficacy and safety of low carbohydrate diets (LCDs) and very low carbohydrate diets (VLCDs) for people with type 2 diabetes (1)
- eligible studies:
- randomized clinical trials evaluating LCDs (<130 g/day or <26% of a 2000 kcal/day diet) and VLCDs (<10% calories from carbohydrates) for at least 12 weeks in adults with type 2 diabetes were eligible
- results:
- searches identified 14759 citations yielding 23 trials (1357 participants), and 40.6% of outcomes were judged to be at low risk of bias
- at six months, compared with control diets, LCDs achieved higher rates of diabetes remission (defined as HbA1c <6.5%) (76/133 (57%) v 41/131 (31%); risk difference 0.32, 95% confidence interval 0.17 to 0.47; 8 studies, n=264, I2=58%)
- conversely, smaller, non-significant effect sizes occurred when a remission definition of HbA1c <6.5% without medication was used
- subgroup assessments determined as meeting credibility criteria indicated that remission with LCDs markedly decreased in studies that included patients using insulin
- att 12 months, data on remission were sparse, ranging from a small effect to a trivial increased risk of diabetes
- large clinically important improvements were seen in weight loss, triglycerides, and insulin sensitivity at six months, which diminished at 12 months
- on the basis of subgroup assessments deemed credible, VLCDs were less effective than less restrictive LCDs for weight loss at six months
- however, this effect was explained by diet adherence. That is, among highly adherent patients on VLCDs, a clinically important reduction in weight was seen compared with studies with less adherent patients on VLCD
- participants experienced no significant difference in quality of life at six months but did experience clinically important, but not statistically significant, worsening of quality of life and low density lipoprotein cholesterol at 12 months. Otherwise, no significant or clinically important between group differences were found in terms of adverse events or blood lipids at six and 12 months
- study authors concluded:
- on the basis of moderate to low certainty evidence, patients adhering to an LCD for six months may experience remission of diabetes without adverse consequences
Study evidence showed that among people with T2D, greater adherence to LCD patterns that emphasize high-quality sources of macronutrients was significantly associated with lower total, cardiovascular, and cancer mortality (2)
Reference:
- Goldenberg JZ et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data.BMJ 2021;372:m4743
- Hu Y et al. Low-Carbohydrate Diet Scores and Mortality Among Adults With Incident Type 2 Diabetes. Diabetes Care 2023; dc222310. https://doi.org/10.2337/dc22-2310