Presence of GAD antibodies during gestational diabetes mellitus predicts type 1 diabetes.

OBJECTIVE We sought to study the frequency of beta-cell-specific autoantibody markers in women with gestational diabetes mellitus (GDM) and to follow these women to estimate the risk of later development of type 1 diabetes. RESEARCH DESIGN AND METHODS Of 385 pregnant women with GDM during 1995-2005 in the district of Lund, 24 (6%) women were found positive for at least one of the following: islet cell antibody (ICA), GAD antibody (GADA), or tyrosine phosphatase antibody (IA-2A). The women were followed and autoantibodies reanalyzed. Those who had not developed diabetes did an oral glucose tolerance test. The frequencies of known risk factors for GDM were compared in women with GDM with and without pancreatic autoantibodies. RESULTS Among the autoantibody-positive women, 50% had developed type 1 diabetes compared with none among the GDM control subjects (P = 0.001), 21% had impaired fasting glucose or impaired glucose tolerance compared with 12.5% among control subjects (P = 0.3), and none had developed type 2 diabetes compared with 12.5% among control subjects (P = 0.1). CONCLUSIONS Autoantibody screening in pregnant women with GDM and follow-up after delivery should be considered for early recognition of type 1 diabetes.