Type b insulin resistance in a 15-year-old white youth

Does obesity cause type 2 diabetes mellitus (T2DM)? Or is it the opposite?

Obesity is believed to be a promoter of type 2 diabetes mellitus (T2DM). Reports indicate that severe obesity in childhood and adolescence increases the risk of T2DM in youth and young adults. T2DM, which is commonly asymptomatic, frequently is not recognized until random blood glucose is measured. Screening blood glucose levels measured in obese individuals are more effective for identifying undiagnosed persons, than screening the general population and therefore introduces a selection bias for discovery. The following commentary will indicate why these observations do not indicate that obesity is the cause of T2DM. Also, it will be shown that the insulin resistance of T2DM occurs primarily in the muscles of lean individuals predisposed to diabetes before they become obese. This insulin resistance is not secondary to, but instead, is the cause of the excessive fat accumulation associated with T2DM. Moreover, this early muscle insulin resistance is the etiology of the hyperlipidemia and excess fat accumulation characteristic of T2DM.

Non-insulin-dependent diabetes mellitus in childhood and adolescence

NIDDM in children and adolescents represents a heterogeneous group of disorders with different underlying pathophysiologic mechanisms. Most subtypes of NIDDM that occur in childhood are uncommon, but some, such as early onset of "classic" NIDDM, seem to be increasing in prevalence. This observed increase is thought to be caused by societal factors that lead to sedentary lifestyles and an increased prevalence of obesity. In adults, hyperglycemia frequently exists for years before a diagnosis of NIDDM is made and treatment is begun. Microvascular complications, such as retinopathy, are often already present at the time of diagnosis. Children are frequently asymptomatic at the time of diagnosis, so screening for this disorder in high-risk populations is important. Screening should be considered for children of high-risk ethnic populations with a strong family history of NIDDM with obesity or signs of hyperinsulinism, such as acanthosis nigricans. Even for children in these high-risk groups who do not yet manifest hyperglycemia, primary care providers can have an important role in encouraging lifestyle modifications that might delay or prevent onset of NIDDM.

Excess insulin binding to insulin-like growth factor receptors: proposed mechanism for acanthosis nigricans

Clinical and epidemiologic evidence has shown acanthosis nigricans to be closely related to defective tissue utilization of insulin in a number of previously recognized (e.g., obesity, lipodystrophy, and leprechaunism) as well as recently characterized (e.g., type A and type B syndromes) disorders. This article reviews the relationship of acanthosis nigricans to these insulin-resistant states. It also focuses attention on the possibility that interaction between excessive amounts of circulating insulin with insulin-like growth factor receptors on keratinocytes and dermal fibroblasts leads to the development of acanthosis nigricans.

Acanthosis nigricans: a cutaneous marker of tissue resistance to insulin

Tissue resistance to insulin is a major feature underlying the development of acanthosis nigricans in many patients. We report two unusual cases of acanthosis nigricans with contrasting forms of insulin resistance and propose an algorithm for the evaluation of patients with acanthosis nigricans. Further, we present a schematic framework that emphasizes the role of insulin and insulin growth factors in the pathogenesis of acanthosis nigricans.

Cutaneous manifestations of diabetes mellitus in children

This article reviews skin changes occurring in diabetic children. Skin changes may be related to metabolic alterations associated with diabetes. Others may be manifestations of macro or microvascular disease. Insulin injections, required for management of most diabetes in the pediatric age group, may also cause cutaneous changes. There remain several cutaneous abnormalities which are observed with increased frequency among diabetics, the significance of which is unknown. The skin is a potentially invaluable tool for understanding certain diabetic complications; however, the value of observations and experimental data relating to cutaneous changes in diabetics depends upon documentation of the type of diabetes mellitus employing the currently accepted classification system.