Lack of plasma albumin enhances glucose tolerance and insulin secretion

Abstract

Congenital analbuminemic individuals and rats (NAR) present several metabolic abnormalities, such as hypertriglyceridemia and plasma free fatty acids (FFA) deficiency. We aimed at studying glucose homeostasis and insulin secretion in these dyslipidemic NAR. Measurements of plasma biochemical variables, insulin levels, isolated islet insulin secretion and glucose homeostasis tests were performed in female NAR and age‐matched controls (SDR, Sprague‐Dawley rats). Plasma glucose levels were similar in fed and fasted NAR and SDR. However, insulinemia was higher in fed NAR than in SDR (P ≤ 0.05). NAR showed increased glucose tolerance compared to SDR (P ≤ 0.05). This enhanced glucose tolerance was associated with higher insulinemia after the glucose load, and with similar insulin sensitivity between groups. Compared to SDR, isolated islets from NAR secreted more insulin in response to glucose and leucine. Despite similar liver glycogen content in fully fed condition, NAR had lower glycogen content (40% of control) after 6‐h fasting. The injection of pyruvate (gluconeogenic substrate) elicited a faster rise in glycemia in NAR than in SDR. In conclusion, NAR display enhanced glucose tolerance, insulin secretion, and gluconeogenesis rate. The higher glucose tolerance is attributed to enhanced islet responsiveness to secretagogues, while peripheral insulin sensitivity is not altered.