Gestational diabetes is on the rise. The finding is not surprising given the dramatic increases in obesity and type 2 diabetes in recent years, but until now few studies have examined trends in gestational diabetes mellitus (GDM) in populations other than the Pima Indians, reported Dana Dabelea, M.D., of the University of Colorado, Denver, and her associates (Diabetes Care 2005;28:579-84).
The findings from Kaiser Permanente of Colorado's perinatal database include all 36,403 pregnancies among 30,216 initially nondiabetic women who delivered singleton infants from 1994 to 2002 and had been screened at 24-28 weeks by the same protocol: a 1-hour 50-g oral glucose tolerance test (OGTT), followed by a diagnostic 3-hour 100-g OGTT among those with glucose values at or above 140 mg/dL on the 50-g test.
A total of 1,183 pregnancies were complicated by GDM from 1994 to 2002. The prevalence of GDM during that time almost doubled—from 2.1% in 1994 to 4.1% in 2002. The rate increased by an average of 12% per year during that period.
The rise in GDM occurred in all ethnic groups, from 1.9% to 3.4% in non-Hispanic whites, 2.8% to 5.1% among Hispanics, 2.5% to 4.6% in African Americans, and 6.3% to 8.6% among Asians. Throughout the study period, pregnant women of all the minority ethnic groups combined consistently had a twofold higher prevalence of GDM than did white women.
When broken down by the mother's birth period, the prevalence of GDM was approximately 40% higher for each successive birth decade from 1946 to 1990. This finding probably reflects women's exposure to increasing rates of obesity in later versus earlier time periods. Obesity is one of the strongest risk factors for GDM, Dr. Dabelea and her associates said.