Abstract
Experience with pellagra in the USA in the 1930s gave clues to the importance of vitamin B3 in diabetes mellitus. Evidence from the literature, both clinical and experimental, that demonstrates the importance of vitamin B3 in diabetes mellitus is discussed here. It is hypothesized that nicotinic acid and nicotinamide have separate, equally important, roles in treatment; nicotinamide may alleviate the beta-cell effect in Type I diabetes and protect against further damage, and nicotinic acid may benefit the insulin resistance, and consequent problems, characteristic of Type II diabetes. Several short cases are presented, demonstrating the potential therapeutic benefits of vitamin B3 in diabetes.