Effects of breakfast macronutrient composition on postprandial glycemic control in patients with diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials.

As the first meal of the day, breakfast significantly impacts the daily blood glucose profile of people with diabetes. However, there is currently no consensus on the optimal macronutrient composition of breakfast (i.e., the appropriate ratio of carbohydrates, protein, fat, and dietary fiber). This systematic review and network meta-analysis aims to evaluate the effects of different macronutrient compositions in breakfast on postprandial blood glucose control in people with diabetes. We searched the PubMed and Web of Science databases for studies published from the inception of each database through March 23, 2026. We included randomized controlled trials comparing the effects of different breakfast macronutrient compositions on glucose-related outcomes in patients with diabetes. Two researchers independently conducted literature screening, data extraction, and risk-of-bias assessments (using the RoB 2.0 tool). We conducted pairwise and network meta-analyses using a random-effects model. Effect sizes were reported as standardized mean differences or mean differences with 95% confidence intervals. Interventions were ranked using the SUCRA score. A total of 25 randomized controlled trials were included. Compared with a standard breakfast, adjusting the macronutrient composition of breakfast significantly reduced 2-hour postprandial blood glucose (mean difference = -1.90 mmol/L; 95% confidence interval: -2.46 to -1.34; P< 0.001), glycated hemoglobin (mean difference = -0.52%; 95% confidence interval: -0.59% to -0.45%; P< 0.001), and the area under the postprandial glucose curve (standardized mean difference = -1.24; 95% confidence interval: -2.45 to -0.03; P = 0.045). Subgroup analyses showed that legume-based breakfasts and low-glycemic-index breakfasts were most effective in reducing 2-hour postprandial blood glucose, while breakfasts supplemented with whey protein were most effective in improving HbA1c. Network meta-analysis and SUCRA ranking indicated that legume-based breakfasts (85.7%) and low-glycemic-index breakfasts (71.4%) were the preferred breakfast choices. No significant publication bias was detected, and the results of sensitivity analyses were robust. Adjusting the macronutrient and dietary fiber composition of breakfast can significantly improve postprandial blood glucose control in people with diabetes. Legume-based breakfasts and low-glycemic-index breakfasts were most effective at lowering 2-hour postprandial blood glucose levels, while breakfasts supplemented with whey protein were most effective at reducing HbA1c. https://www.crd.york.ac.uk/PROSPERO/, identifier CRD420261367773.