Amount and type of
dietary carbohydrate (CHO), as well as the CHO:fat ratio, are thought to be critical for both the rate of development and severity of
Type 2 diabetes mellitus. Thus, these nutritional considerations were examined in the previously described "spontaneous" model of diabetes and
metabolic syndrome, the Nile rat. Weanling male Nile rats (n=92) were fed semipurified diets, modifying glycemic index and load by changing the amount of fiber or altering the CHO:fat ratio. Random and fasting
blood glucose and
body weight were assessed, and diabetes was characterized in terms of
blood glucose, relevant plasma and liver parameters, food and water intake and terminal organ weights. Nile rats fed with hiCHO became more hyperglycemic than rats fed with modCHO (P<.05), while loCHO and hiCHO+hiFiber rats remained essentially normoglycemic. Liver
lipid and
glycogen accumulation was associated with severe
hyperlipemia in diabetic rats, analogous to
metabolic syndrome in humans. Advanced diabetes was linked to liver and kidney damage and elevated blood
urea nitrogen with
weight loss. Dispersing dietary CHO by fiber or replacing it by moderate fat (reducing the glycemic index and load) delayed the onset of diabetes but did not prevent signs of
insulin resistance. A very low content of dietary CHO (high fat) seemed to prevent even these early indicators of
insulin resistance. Thus, the Nile rat represents a novel CHO-sensitive model for study of
Type 2 diabetes that reliably follows the course of disease in humans.