Nutritional recovery with a soybean flour diet improves the insulin response to a glucose load without modifying glucose homeostasis

Objective We investigated the effect of nutritional recovery with a soybean flour diet on glucose tolerance, insulin response to a glucose load, and the action of insulin in adult rats exposed to a protein deficiency during intrauterine life and lactation. Methods Male Wistar rats from dams fed a normal- or low-protein diet during pregnancy and lactation were maintained after weaning by feeding them normal-protein isoenergetic diets containing soybean flour or casein and low-protein casein diet. Results Rats fed a soybean flour diet had a lower final body weight, epididymal fat pad, carcass fat content, and liver glycogen level. The serum glucose concentrations in the basal and fed states and the area under the glucose curves during the glucose tolerance test were not significantly different among the four groups. Their serum insulin levels during fasting were observed to be similar to those fed a casein diet. These rats also had a higher serum insulin levels in a fed state and total area under the insulin curves in response to a glucose load, but a lower ratio of area under the glucose/insulin curves during the glucose tolerance test than those fed a casein diet. Conclusion These results indicate that nutritional recovery with a soybean flour diet improved the insulin response to a glucose load and decreased the sensitivity to insulin, at least in hepatic tissue.