Effect of the ketogenic diet on glycemic control, insulin resistance, and lipid metabolism in patients with T2DM: a systematic review and meta-analysis.

Nutrition & diabetes. 2020;10(1):38


BACKGROUND At present, the beneficial effect of the ketogenic diet (KD) on weight loss in obese patients is generally recognized. However, a systematic research on the role of KD in the improvement of glycemic and lipid metabolism of patients with diabetes is still found scarce. METHODS This meta-study employed the meta-analysis model of random effects or of fixed effects to analyze the average difference before and after KD and the corresponding 95% CI, thereby evaluating the effect of KD on T2DM. RESULTS After KD intervention, in terms of glycemic control, the level of fasting blood glucose decreased by 1.29 mmol/L (95% CI: -1.78 to -0.79) on average, and glycated hemoglobin A1c by 1.07 (95% CI: -1.37 to -0.78). As for lipid metabolism, triglyceride was decreased by 0.72 (95% CI: -1.01 to -0.43) on average, total cholesterol by 0.33 (95% CI: -0.66 to -0.01), and low-density lipoprotein by 0.05 (95% CI: -0.25 to -0.15); yet, high-density lipoprotein increased by 0.14 (95% CI: 0.03-0.25). In addition, patients' weight decreased by 8.66 (95% CI: -11.40 to -5.92), waist circumference by 9.17 (95% CI: -10.67 to -7.66), and BMI by 3.13 (95% CI: -3.31 to -2.95). CONCLUSION KD not only has a therapeutic effect on glycemic and lipid control among patients with T2DM but also significantly contributes to their weight loss.

Expert Review

Conflicts of interest: None
Take Home Message: A ketogenic diet may be a useful dietary intervention for type 2 diabetics with the potential to: ● Reduce fasting blood glucose ● Reduce HBA1c ● Reduce triglycerides, total cholesterol and LDL ● Increase HDL ● Promote weight loss ● Positive results were observed within in a minimum time frame of 1 week Based on the findings, the ketogenic diet may prove beneficial as a component of an integrated approach for the management of type 2 diabetes.
Evidence Category:
  • X A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
  • B: Systematic reviews including RCTs of limited number
  • C: Non-randomized trials, observational studies, narrative reviews
  • D: Case-reports, evidence-based clinical findings
  • E: Opinion piece, other
Summary Review: Type 2 diabetes has become a worldwide health burden with a global prevalence of 300 million. Being overweight or obese has demonstrated to be a significant risk factor for the development of type 2 diabetes. The ketogenic diet which can be characterised by a diet of <55g of carbohydrates daily has demonstrated to be a beneficial intervention for weight loss and glycemic control suggesting potential utility for type 2 diabetics. This systematic review and meta-analysis compared the effects of a ketogenic diet on markers of glycemic control, lipid metabolism and body weight in type 2 diabetics pre and post intervention. There were a total of 13 studies and 567 subjects included in this meta-analysis. The findings conclude that type 2 diabetics following a ketogenic diet intervention ranging from 1-56 weeks experienced an average reduction of fasting blood glucose of 1.29mmol/l, HBA1c reduced by 1.07%, triglycerides decreased by 0.72 mmol/L , total cholesterol decreased by 0.33 mmol/L, LDL decreased by 0.05 mmol/L, HDL increased by 0.14 mmol/L, the average body weight decreased by 8.66 kg , waist circumference reduced by 9.17 cm and BMI reduced by 3.13 kg/m2.
Clinical practice applications: This meta-analysis demonstrates that a ketogenic diet may be a useful dietary intervention to improve glycemic control, lipid metabolism and body weight in Caucasian type 2 diabetics. Positive results were seen within as little as 1 week. Macronutrient ratios of included studies: * Carbohydrates: <50g/d - 15g/d ● Protein: 20-28% or 1.5g/kg or 72-100g per day ● Fats: 58%-75% or to satiety Adverse reactions to the ketogenic diet were mentioned in two of the studies. In the first study, fatigue, headache, nausea and vomiting were more common amongst the ketogenic diet group following 2 weeks of the intervention, while constipation and orthostatic hypotension were more commonly observed following 10 weeks. Symptoms of increased hunger, headache, nausea, vomiting, constipation and diarrhea were observed in subjects following a ketogenic diet in a second study. The symptoms were categorised as mild and not related to clinical practice.
Considerations for future research: This meta-analysis only included 13 studies with primarily Caucasian patients due to limited available clinical trials. Further research is needed in order to determine risk/benefit of the ketogenic diet in type 2 diabetics amongst different populations and ethnic groups, particularly where type 2 diabetes is more prevalent. Follow-up periods ranged from 1-56 weeks. Longer-term studies would be useful to assess potential risks or benefits that would present over a longer time period.

Methodological quality