Abstract: BACKGROUND: The ketogenic diet (KD), a high-fat, very low-carbohydrate dietary approach, has gained popularity for weight loss and metabolic control. However, its long-term efficacy and safety in obese adults with type 2 diabetes mellitus (T2DM) remain unclear. OBJECTIVE: To determine the effects and adverse events associated with KDs on metabolic parameters – particularly low-density lipoprotein cholesterol (LDL-C) – in overweight and obese adults with T2DM. METHODS: We conducted a systematic review and meta-analysis of randomized controlled trials comparing KDs (≤10% carbohydrates) with non-KDs for at least 3 months. Eligible participants were adults with a body mass index ≥25 and T2DM. Databases searched included PubMed, Cochrane, EMBASE, Google Scholar, and HERDIN. The primary outcome was LDL-C. Secondary outcomes included high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), fasting blood sugar, glycated hemoglobin (HbA1c), and adverse events. Risk of bias was assessed via ROB 2.0 and GRADE. RESULTS: Nine studies (658 participants) were included. At 3–4 months, KD significantly reduced LDL-C (mean difference: −0.16 mmol/L; 95% confidence interval: −0.31, −0.00; P = 0.04). This effect was not sustained at 6–24 months. Significant short-term improvements were also observed in HDL-C, TG, and HbA1c. HDL-C showed increasing benefits over time (meta-regression P = 0.047). Adverse events included hypoglycemia, constipation, and fatigue, but malnutrition was rare. CONCLUSION: KDs offer modest short-term benefits in lipid and glycemic control among obese adults with T2DM, particularly within 3–6 months. However, benefits diminish over time, and adverse effects require careful monitoring. Further long-term studies are warranted.
Juan et al. (2026) studied this question.