Читать книгу Gestational Diabetes - Группа авторов - Страница 29

Gestational diabetes is characterized by an exaggeration of the normal pathophysiologic changes of pregnancy superimposed upon a dampening of the necessary compensation in insulin secretion. Some studies show that women with GDM appear to release more insulin than controls, but not enough to overcome their insulin resistance. For example, the plasma insulin response to an intravenous glucose tolerance test was greater in normal weight [60] and obese [61] women with gestational diabetes compared to controls, while insulin sensitivity was lower in GDM and endogenous glucose production was less suppressible in GDM. Other studies suggest that women with GDM release less insulin than nondiabetic pregnant controls, with similar insulin resistance [62]. Because much of the insulin released from the pancreas is cleared by the liver before reaching the periphery, one study [63] estimated prehepatic insulin secretion rates utilizing C-peptide kinetics and hyperglycemic clamp methodology. Overweight or obese (BMI 36 ± 2) women with gestational diabetes demonstrated similar prehepatic insulin secretion rates to overweight or obese (BMI 31 ± 20) controls in the basal state, but their prehepatic insulin secretion rates were 19% lower than controls during hyperglycemia. While risk factors for GDM such as overweight and obesity reflect increased insulin resistance, it is most likely that women with GDM also have a β-cell defect, similar to those with type 2 diabetes.