ISLET AMYLOID POLYPEPTIDE (AMYLIN) DOES NOT SEEM TO BE DIRECTLY INVOLVED IN THE DEVELOPMENT OF GESTATIONAL DIABETES-MELLITUS

In order to define the islet amyloid polypeptide (IAPP) levels in gest ational diabetes mellitus (GDM) and their interrelationship with the i nsulin levels, we studied (1) the placental RNA from 10 women (5 with GDM and 5 normals) for IAPP expression by Northern blotting and (2) 10 women with GDM during a 100-gram oral glucose tolerance test and comp ared these with 11 normal women matched for obesity and age. Plasma le vels of glucose, IAPP, insulin, and C peptide were determined. No IAPP expression was detected in any of the placentae after a long exposure . We could not demonstrate any differences in plasma IAPP levels (basa l or stimulated) between the two groups of pregnant women. However, in women with GDM we found a lower IAPP/insulin ratio (p < 0.05) and a l ower maximal IAPP/maximal insulin response ratio during the oral gluco se tolerance test (p < 0.05) than in normal women. Therefore, IAPP doe s not appear to be directly involved in the development of GDM. The pe ripheral levels of IAPP relative to insulin are lower in GDM, a findin g similar to that described in type 2 diabetes mellitus (non-insulin-d ependent diabetes mellitus). This observation further confirms that GD M resembles the early stages of type 2 diabetes mellitus.