Type II diabetes and syndrome X. Pathogenesis and glycemic management.

Non-insulin-dependent diabetes (NIDDM) has long been recognized as being associated with a cluster of disorders including obesity, hypertension, dyslipidemia, and atherosclerotic heart disease. It was only recently, however, that Reaven, DeFronzo, and Ferrannini with techniques to quantitate insulin resistance suggested that this represents a common factor in this group of disorders and that hyperinsulinemia resulting from insulin resistance could be the cause of the hypertension, dyslipidemia, and atherosclerosis. The names syndrome X or the insulin-resistance syndrome have been used to identify this pathological entity, and considerable investigations have been done and are in progress to establish whether or not these coexisting disorders represent an as yet unexplained association of cardiovascular risk factors or if, indeed, insulin resistance and hyperinsulinism represent the primary cause for most of the other disorders. To paraphrase a philosophical comment, if syndrome X did not exist, we probably would have had to invent it. In addition to the intellectual satisfaction of being able to "lump" these diverse ills under a single etiology, the main value of grouping these disorders as a syndrome is to continually remind physicians that the therapeutic goals are not only to correct hyperglycemia in NIDDM but also to manage the elevated blood pressure and dyslipidemia that cause cerebrovascular and cardiac morbidity as well as mortality in these patients. Having a syndrome X reduces the fragmentation of medical care among subspecialties and decreases the likelihood of prescribing drugs that correct hypertension but raise lipids or drugs that lower lipids but raise blood glucose. Finally, it encourages the selection of drugs that reduce hyperglycemia without increasing insulin secretion and to the development of new drugs for this purpose. Unfortunately, the concept of insulin resistance with hyperinsulinism being a cause of the other associated disorders is still unproved but continues to be open to experimental investigation. The remainder of this article reviewed the use of sulfonylureas in the management of NIDDM, discussed new molecular and cellular mechanisms by which they promote insulin secretion, and reviewed the controversy as to whether an extrapancreatic action contributes to their glucose-lowering effects in NIDDM. A closing section listed some other oral drugs that can lower blood glucose without stimulating the pancreatic beta cell. Their insulin-sparing hypoglycemic effect makes them potentially useful in NIDDM therapy, particularly if the fundamental premise of syndrome X is substantiated, which implicates hyperinsulinemia as contributing to the morbidity and mortality from atherosclerotic vascular disease.