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

Abstract

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.

Fig. 1. PRISM diagram for the systematic review.

Only studies published in English were considered, which were identified by searching the PubMed and MEDLINE databases. The keywords used for this literature search are T2DM or diabetes mellitus, ketogenic diet, obesity, and human. The search was finished on September 20, 2019.

Fig. 2. Forest plots for blood glucose and HbA1c.

The reduced proportion of HbA1c is more significant after the KD implementation, which is regarded as the ideal therapeutic effect of drugs that is possible to be achieved on HbA1c.

Fig. 3. Forest plots for TC, TG, LDL, and HDL.

It can be seen that after KD consumption, TG, TC, and LDL decreased. On the other hand, HDL increased.

Fig. 4. Forest plots for body weight, waist circumference, and BMI.

Many studies have demonstrated that KD has a positive effect by providing effective control over obesity; our findings were consistent with the previous reports.