Association between dietary carbohydrate intake and risk of type 2 diabetes: a systematic review and meta-analysis of cohort studies

BackgroundPrevious meta-analyses have assessed the relationship between carbohydrate intake and type 2 diabetes (T2D) risk; however, they included few studies of Asian populations who have a higher carbohydrate intake and lower insulin secretory capacity than non-Asians. Since the publication of the previous meta-analyses, three further studies of Asian populations have been conducted. Based on this background, the present study aimed to perform an updated systematically examine observational studies concerning the link between dietary carbohydrate intake and T2D risk.MethodsWe conducted a systematic search for cohort studies that investigated the target association. For each analyzed study, parameter-adjusted risk ratios were used to compare the lowest and highest carbohydrate-intake groups in terms of their risk of incident T2D. The risk ratios were calculated using a random-effects model.ResultsTen publications were analyzed. Overall, carbohydrate intake was found not to be associated with increased risk ratios of incident T2D (risk ratio [RR] = 1.07; 95% confidence interval [95% CI] = 0.94, 1.21; P < 0.01, I-2 = 61.9%). However, studies of Asian populations reported that high carbohydrate intake is significantly associated with this risk (RR = 1.29; 95% CI 1.15, 1.45; P = 0.59, I-2 = 0.0%).ConclusionsThis updated meta-analysis showed that, overall, carbohydrate intake is not associated with the risk of T2D; nevertheless, a significant association exists among Asian populations. To confirm the association between dietary carbohydrate intake and T2D risk observed in this study, further evidence from long-term observational studies of Asian populations is required.