Building Competency in Diabetes Education THE ESSENTIALS

3-18 | CHAPTER 3

Polycystic ovarian syndrome Polycystic ovarian syndrome (PCOS) is a common condition in premenopausal women characterized by anovulation and high levels of androgens (hyperandrogenism). Insulin resistance is a feature found in a substantial number of women with PCOS. PCOS significantly increases the risk of developing type 2 diabetes independent of abnormal weight in these women (5). Insulin resistance Insulin resistance is due to diminished insulin action secondary to intracellular (i.e. post receptor) abnormalities in cell signalling, which have not been completely defined. The precise molecular processes resulting in insulin resistance in type 2 diabetes have not been elucidated. However, it is likely that several factors contribute to the impaired insulin action of insulin resistance (30), as shown in Figure 3.

Figure 3. Pathogenesis of insulin resistance

Genetic

Environment*

Obesity

Insulin resistance

* Environment refers to a variety of factors, including hormones, increased nutrient availability and age.

Skeletal muscle, adipose tissue and the liver are the principal sites of insulin resistance. Consequently, there is increased hepatic glucose production and decreased glucose transport at the muscle. Not only does the obesity epidemic correlate with the epidemic of type 2 diabetes, but adipose tissue is now recognized as an endocrine organ with significant effects (13,15,30). White adipose tissue influences insulin action through release of FFAs and by secretion of adipose-derived proteins, such as adiponectin, leptin and resistin, and by proinflammatory molecules (adipokines) (30). Most patients with type 2 diabetes (approximately 80%) are obese, and their insulin resistance may improve with weight loss. However insulin resistance has also been described in lean patients with type 2 diabetes (24,25,29). Hyperglycemia itself can also cause insulin resistance, so people with type 1 diabetes in poor control are also insulin-resistant. Adolescence and