Effect of dietary carbohydrate type, biological sex and phenotype on glycemic responses in wistar fatty rats

Abstract

To determine the effects of dietary carbohydrate type, biological sex, and phenotype on systemic glycemic responses in a rat strain that Is highly predisposed to development of obesity+NIDDM, groups of adult male and female lean and obese Wistar Fatty Rats were fed nutritionally complete isoenergetic diets containing 54% carbohydrate as cornstarch (ST) or sucrose (SUC) plus other essential nutrients, vitamins, and minerals from 22 until 30 weeks of age. Measures of body weight gain (BWG), Food efficiency ratio (FER), intraperitoneal Glucose Tolerance (ipGTT), fasting insulin to glucose ratios (I: G), and area under the glucose curve (AUC) determined. Results demonstrated that BWG and FER of obese >> lean and was further increased in both phenotypes when fed the SUC diet. The ipGTT responses of obese > lean in both sexes, and that substitution of SUC for ST markedly exaggerated the glycemic responses and glycosuria in both sexes. Fasting of insulin concentrations were greater in obese male than obese female, were further increased when fed the SUC diet and were significantly greater in the obese than occurred in the lean phenotype of either sex. Fasting glucose concentrations of male obese+NIDDM were elevated but remained within normal limits in the remaining groups. The I:G ratios were greatest in Obese+NIDDM male rats, intermediate in the obese+NIDDM female rats, and were within normal range in both lean groups on ST and SUC diets and the AUC of obese > lean of obese sexes and was further increased when fed the SUC diet in both sexes. These results confirm that feeding a high glycemic index sucrose rich diet enhances the efficiency and amount of weight gain and exacerbates the aberrant glycemic responses during ipGTT in the obese+NIDDM phenotype.