Dietary carbohydrates may influence the development of type 2 (non-insulin-dependent)
diabetes, for example, through effects on blood glucose and insulin concentrations.
We examined the relations of baseline intake of carbohydrates, dietary fiber, dietary
magnesium, and carbohydrate-rich foods and the glycemic index with incidence of diabetes.
This was a prospective cohort study of 35988 older Iowa women initially free of diabetes.
During 6 y of follow-up, 1141 incident cases of diabetes were reported.
Total grain, whole-grain, total dietary fiber, cereal fiber, and dietary magnesium
intakes showed strong inverse associations with incidence of diabetes after adjustment
for potential nondietary confounding variables. Multivariate-adjusted relative risks
of diabetes were 1.0, 0.99, 0.98, 0.92, and 0.79 (P for trend: 0.0089) across quintiles
of whole-grain intake; 1.0, 1.09, 1.00, 0.94, and 0.78 (P for trend: 0.005) across
quintiles of total dietary fiber intake; and 1.0, 0.81, 0.82, 0.81, and 0.67 (P for
trend: 0.0003) across quintiles of dietary magnesium intake. Intakes of total carbohydrates,
refined grains, fruit and vegetables, and soluble fiber and the glycemic index were
unrelated to diabetes risk.
These data support a protective role for grains (particularly whole grains), cereal
fiber, and dietary magnesium in the development of diabetes in older women.