Glycemic index

Type 2 diabetes

Endocrinology

Body mass index

Environmental health

Glycemic load

Glycemic

Meta-analysis

Internal medicine

Confidence interval

Overweight

Hazard ratio

Medicine

Obesity

Diabetes mellitus

Nutrition Metabolism and Cardiovascular Diseases

Background and aimsDespite the proven evidence of high glycemic index (GI) and glycemic load (GL) diets to increase cardiometabolic risks, knowledge about the meta-evidence for carbohydrate quality within world geographic regions is limited. We conducted a meta-analysis to synthesize the evidence of GI/GL studies and carbohydrate quality, gathering additional exposures for carbohydrate, high glycemic carbohydrate, total dietary fiber, and cereal fiber and risks for type 2 diabetes (T2DM), coronary heart disease (CHD), stroke, and mortality, grouped into the US, Europe, and Asia. Secondary aims examined cardiometabolic risks in overweight/obese individuals, by sex, and dose–response dietary variable trends.Methods and results40-prospective observational studies from 4-Medline bibliographical databases (Ovid, PubMed, EBSCOhost, CINAHL) were search up to November 2019. Random-effects hazard ratios (HR) and 95% confidence intervals (CI) for highest vs. lowest categories and continuous form combined were reported. Heterogeneity (I2>50%) was frequent in US GI/GL studies due to differing study characteristics. Increased risks ((HRGI,T2DM,US=1.14;CI:1.06,1.21), HRGL,T2DM,US=1.02 (1.01, 1.03)), HRGI,T2DM,Asia=1.25;1.02,1.53), and HRGL,T2DM,Asia=1.37 (1.17, 1.60)) were associated with cardiometabolic diseases. GI/GL in overweight/obese females had the strongest magnitude of risks in US-and Asian studies. Total dietary fiber (HRT2DM,US = 0.92;0.88,0.96) and cereal fiber (HRT2DM,US = 0.83;0.77,0.90) decreased risk of developing T2DM. Among females, we found protective dose–response risks for total dietary fiber (HR5g-total-dietary-fiber,T2DM,US = 0.94;0.92,0.97), but cereal fiber showed better ability to lower T2DM risk (HR5g-cereal-fiber,T2DM,US = 0.67;0.60,0.74). Total dietary-and cereal fibers' dose–response effects were nullified by GL, but not so for cereal fiber with GI.ConclusionsOverweight/obese females could shift their carbohydrate intake for higher cereal fiber to decrease T2DM risk, but higher GL may cancel-out this effect.

Carbohydrate quality, glycemic index, glycemic load and cardiometabolic risks in the US, Europe and Asia: A dose–response meta-analysis