Effects of administration of nicotinic acid on glucose, insulin, and glucose tolerance in ruminants.

Effects of nicotinic acid on glucose metabolism were studied in a series of experiments with goats. Oral administration of single doses of nicotinic acid (6.5 to 17.0 g) elevated blood glucose, impaired glucose tolerance, and elevated insulin. The magnitude of the effects was related positively to nicotinic acid dosage. Maximum effect occurred 2 to 3 days after administration. Blood glucose was elevated, with or without glucose administration, despite markedly elevated insulin. However, exogenous insulin given 48 h after nicotinic acid still reduced blood glucose although the response was delayed and was less than in control animals. A lactating cow given 160 g nicotinic acid exhibited alterations in glucose metabolism similar to control animals. These studies demonstrate that nicotinic acid, in addition to previously reported effects on lipid metabolism, also has significant effects on carbohydrate metabolism.