Gestational diabetes mellitus appears to increase the risk of developing diabetes later in life, Finnish investigators report in Diabetes Care.

Dr. Juha S. Tapanainen, of Oulu University Hospital, Finland, and colleagues followed 435 women with gestational diabetes and 435 healthy women (controls) for about six years.

A total of 20 women (4.6 percent) in the gestational diabetes group developed type 1 diabetes and 23 women (5.3 percent) developed type 2 diabetes. None of the control subjects became diabetic.

One hundred fifty-five women (35.6 percent) with gestational diabetes were treated with insulin during pregnancy. Of the 20 women with gestational diabetes who developed type 1 diabetes, 18 (90 percent) had received insulin therapy, and so did 18 of the 23 women (78.3 percent) who developed type 2 diabetes.

Overall, 62.5 percent of women who developed type 1 diabetes tested positive for islet cell antibodies. Only two women who later developed type 2 diabetes tested positive for autoantibodies.

The results of further analysis revealed that women younger than 30 years old who required insulin treatment for gestational diabetes and those who tested positive for autoantibodies had an increased risk of type 1 diabetes.

These women require careful follow-up after pregnancy because an earlier type 1 diabetes diagnosis is associated with a preserved ability to produce insulin and a lower risk of complications of the circulatory system, Dr. Tapanainen’s team advises.

SOURCE: Diabetes Care, March 2006.