[Glucose metabolism and chronic renal insufficiency]

Chronic renal failure is characterized by abnormalities in glucose metabolism. In fact there are present a normal fasting plasma glucose level )or mild hyperglycemia) in the presence of hyperinsulinemia, blunted decrease in the plasma glucose concentration in response to exogenous insulin administration, and diminished effect of intravenous insulin on glucose uptake in forearm perfusion studies. The glucose intolerance is not the result of reduced insulin secretion, or circulating insulin antagonists, and does not correlate with the coexisting metabolic acidosis. Glucose intolerance exists because the peripheral insulin-sensitive tissue (muscle, adipose tissue, liver) of the patients with chronic renal failure are insulin resistant. However there are two subgroups of uremic patients with regard to glucose tolerance: about half of uremic patients can augment their insulin secretion sufficiently to maintain normal glucose tolerance despite glucose intolerance. In the other half, insulin secretion following glucose loads is not different from normal values, so that glucose intolerance results. The cause of the peripheral insulin resistance remain unclear. Besides deranged renal function can result in the development of hypoglycemia. The most important predisposing mechanism to hypoglycemia is diminished glucose availability due to substrate limitation; the second important mechanism (alcohol, insulin, propranolol, etc.). Finally, in chronic renal failure persistent hyperinsulinemia can contribute hyperlipemia and to high incidence of cardiovascular disease.