Effects of very low-carbohydrate ketogenic diet on lipid metabolism in patients with type II diabetes mellitus: a meta-analysis

Objective: to evaluate the lipid metabolism of patients with type 2 diabetes mellitus (T2DM) after very low-carbohydrate ketogenic (VLCK) diet treatment, so as to provide an evidence-based basis for better dietary management and comprehensive treatment of diabetic patients. Methods: PubMed, Cochrane Library, Embase, and Web of Science databases were searched for randomized controlled trial about VLCK diet on lipid metabolism of T2DM up to September 2021. The data were analyzed using the Stata 15.0; standardized mean difference (SMD) was used as effect size. Results: ten articles were included in this meta-analysis. There were no significant differences between the two groups in total cholesterol (SMD = -0.07, 95 % CI: -0.06-0.20, p > 0.05), HDL (SMD = 0.13, 95 % CI: -0.05-0.31, p > 0.05) and LDL (SMD = 0.07, 95 % CI: -0.06-0.20, p > 0.05) levels after treatment. No difference was found in total cholesterol, HDL, and LDL levels between the two groups after 3, 6, and 12 months of treatment (p > 0.05). Triglyceride levels decreased after VLCK diet compared with control (SMD = -0.49, 95 % CI: -0.82 to -0.17, p = 0.003). A marked reduction of triglyceride levels was identified after 3 months of VLCK diet treatment (SMD = -0.69, 95 % CI: -1.00 to -0.38), without significant difference after 6 and 12 months. Conclusion: T2DM patients who receive a VLCK diet to lower blood glucose are not associated with increased levels of total cholesterol and LDL, and decreased levels of HDL. Additionally, this diet can achieve a short-term reduction of triglyceride levels.