Monogenic and other unusual causes of diabetes mellitus.

This article covers some unusual or rare causes of diabetes mellitus chosen not necessarily on the basis of frequency or rarity, but rather on the basis of how well the disease and its implications in diabetes management is understood. A specific diagnosis is of help in these rare syndromes but not absolutely necessary for optimal management. The basic principles of diabetes management are well-defined, regardless of etiology. What is important is to understand the relative contribution of insulin resistance versus insulin deficiency, regardless of etiology, as the most important guide to management.