Effect of Dietary Approaches on Glycemic Control in Patients with Type 2 Diabetes: A Systematic Review with Network Meta-Analysis of Randomized Trials

Abstract

Background: Dietary patterns play a critical role in diabetes management, while the best dietary pattern for Type 2 diabetes (T2DM) patients is still unclear. The aim of this network meta-analysis was to compare the impacts of various dietary approaches on the glycemic control of T2DM patients. Methods: Relevant studies were retrieved from PubMed, Embase, Web of Knowledge, Cochrane Central Register of Controlled Trials (CENTRAL), and other additional records (1949 to 31 July 2022). Eligible RCTs were those comparing different dietary approaches against each other or a control diet in individuals with T2DM for at least 6 months. We assessed the risk of bias of included studies with the Cochrane risk of bias tool and confidence of estimates with the Grading of Recommendations Assessment, Development, and Evaluation approach for network meta-analyses. In order to determine the pooled effect of each dietary approach relative to each other, we performed a network meta-analysis (NMA) for interventions for both HbA1c and fasting glucose, which enabled us to estimate the relative intervention effects by combing both direct and indirect trial evidence. Results: Forty-two RCTs comprising 4809 patients with T2DM were included in the NMA, comparing 10 dietary approaches (low-carbohydrate, moderate-carbohydrate, ketogenic, low-fat, high-protein, Mediterranean, Vegetarian/Vegan, low glycemic index, recommended, and control diets). In total, 83.3% of the studies were at a lower risk of bias or had some concerns. Findings of the NMA revealed that the ketogenic, low-carbohydrate, and low-fat diets were significantly effective in reducing HbA1c (viz., −0.73 (−1.19, −0.28), −0.69 (−1.32, −0.06), and −1.82 (−2.93, −0.71)), while moderate-carbohydrate, low glycemic index, Mediterranean, high-protein, and low-fat diets were significantly effective in reducing fasting glucose (viz., −1.30 (−1.92, −0.67), −1.26 (−2.26, −0.27), −0.95 (−1.51, −0.38), −0.89 (−1.60, −0.18) and −0.75 (−1.24, −0.27)) compared to a control diet. The clustered ranking plot for combined outcomes indicated the ketogenic, Mediterranean, moderate-carbohydrate, and low glycemic index diets had promising effects for controlling HbA1c and fasting glucose. The univariate meta-regressions showed that the mean reductions of HbA1c and fasting glucose were only significantly related to the mean weight change of the subjects. Conclusions: For glycemic control in T2DM patients, the ketogenic diet, Mediterranean diet, moderate-carbohydrate diet, and low glycemic index diet were effective options. Although this study found the ketogenic diet superior, further high-quality and long-term studies are needed to strengthen its credibility.

Eight Weeks of Intermittent Exercise in Hypoxia, with or without a Low-Carbohydrate Diet, Improves Bone Mass and Functional and Physiological Capacity in Older Adults with Type 2 Diabetes

“…A multifactorial approach, including physical exercise and dietary control, leads to success in losing weight and body fat and treating disturbances in glucose metabolism [ 18 ], and is thus able to promote T2DM remission, defined by hemoglobin A1c (HbA1c) < 6.5% [ 19 ]. A low-carbohydrate diet (LCD) is described as a favorable dietary intervention for managing glycemic control in patients with T2DM [ 20 , 21 ]. In practice, LCDs restrict grains, cereals, and legumes, and other foods that contain high carbohydrate contents, such as dairy, some fruits, and certain vegetables.…”

The role of Mediterranean diet in cancer incidence and mortality in the older adults: a systematic review and meta-analysis.

“…Considering its high content of avonoids, omega-three fatty acids, and folic acid, MD can play a role in the in ammaging, hindering subclinical in ammation and thus slowing and retarding of cell senescence: these molecules interact synergistically in bene cially affecting several metabolic pathways, including the glycaemic control. 40 Moreover, there is evidence that MD anti-in ammatory and antioxidative properties can impact telomere length: a recent meta-analysis found an association between MD adherence and shortening, which is associated with biological aging. 41 In addition, mounting evidence con rms the inverse association between MD adherence and obesity, a known risk factor for some hormone-sensitive neoplasia: this is related to body weight reduction and to reduced risk of gaining weight over time with adherence to MD.…”

Comparative Evaluation of a Low-Carbohydrate Diet and a Mediterranean Diet in Overweight/Obese Patients with Type 2 Diabetes Mellitus: A 16-Week Intervention Study

“…Although there are numerous studies on the potential beneficial effects of low-carbohydrate diets on overweight diabetic patients, there is a paucity of scientific literature that directly compares the effects of an MD versus an LCD as seen in our study [ 58 ]. First, in line with a recent review and meta-analysis of Ajala et al [ 59 ], our study showed that both MD and LCD diets resulted in a significant reduction in weight loss and improvement in blood pressure, glucose control, lipid profile, cardiovascular risk, and renal function after 16 weeks of treatment.…”