Low prevalence of islet autoantibodies in patients with gestational diabetes mellitus.

OBJECTIVE

To determine the proportion of patients with gestational diabetes mellitus (GDM) who have serological characteristics typical of IDDM.

RESEARCH DESIGN AND METHODS

Islet cell antibodies (ICAs), insulin autoantibodies (IAAs), GAD65, and IA-2 antibodies were measured in 145 pregnant women with GDM, 33 with impaired glucose tolerance (IGT), and in 73 with normal glucose tolerance (NGT). ICAs were measured by indirect immunofluorescence; GAD65 and IA-2 antibodies, by a radio-ligand immunoassay incorporating 35S-labeled recombinant antigen; and IAAs, by a liquid-phase radiobinding assay.

RESULTS

The prevalences of islet autoantibodies were low and not significantly different between groups. ICAs were detected at levels ranging from 5 to 45 Juvenile Diabetes Foundation U in 14 (10%) women with GDM, 2 (6%) women with (GT, and in 4 (5%) women with NGT. IAAs were detected at levels between 3 and 4 SD above the mean in 4 (3%) women with GDM, 0 women with IGT, and in 1 (1%) woman with NGT. None had both ICAs and IAAs. Neither GAD65 nor IA-2 antibodies, which have been detected in the majority of pre-IDDM and IDDM patients, were found in NGT, IGT, or GDM patients.

CONCLUSIONS

Low-titer ICAs and IAAs are not infrequent in pregnant women, but multiple islet autoantibodies and antibodies to GAD65 or IA-2 were not found in GDM. These findings suggest that the serological characteristics of IDDM are rare in GDM.