Type 2 diabetes mellitus does not result so clearly from insulin deficiency. Defects in insulin secretion in people with Type 2 diabetes can be unmasked by laboratory tests: in particular, the initial phase of insulin secretion in response to a glucose load appears to be defective at an early stage in the disease. However, the prominent defect in Type 2 diabetes is not so much a deficiency of insulin, as a failure of insulin, at relatively normal concentrations, to exert its normal effects: this is the condition known as insulin resistance (Fig. 10.2). Insulin resistance may have widespread effects (Box 10.1).
Insulin resistance is also a prominent feature of obesity (see Section 11.4.4). One very plausible hypothesis for the development of Type 2 diabetes is the following. When people become obese, their tissues become resistant to the ac-
Was this article helpful?