Glycemic limbo � how low can you go?

Even optimal glycemic control once thought to avoid pregnancy complications in type I diabetes just isn't enough

By Tony Craig

Medical news can make depressing reading for people with diabetes. Our overall picture of this disease has darkened considerably in the last decade. While research in other diseases often highlights promising new treatments, much diabetes research just seems to throw up new risks and complications.

A Dutch study published online ahead of print on April 5 in the British Medical Journal is no exception. The conclusion of this prospective study is that "near optimal maternal glycemic control apparently isn't good enough" to reduce the risks of pregnancy complications in women with type I diabetes compared to the level of the general population.

All 118 hospitals in the Netherlands participated in this study, reporting every woman with type I diabetes that presented for antenatal care between April 1999 and April 2000. After 16% were excluded, mainly due to spontaneous first trimester abortions, 323 subjects remained.

The most important measure in these women was the standard blood glucose level indicator, Hemoglobin A_1c (HbA_1c). Lower than 6% HbA_1c was considered excellent, 6-7% was deemed good, and over 7% was considered suboptimal control. The researchers also collected data on the subjects' age, body mass index, marital status, ethnic origin, education level, alcohol use, smoking habits, parity, and the history of their diabetes. The women in this study were almost all married with a high average level of education. No fewer than 84% of the pregnancies were planned, and 70% of the women had started on folic acid supplements before conception.

The American Diabetes Association (ADA) said that in pregnancy tight glycemic control is accomplished when the patient's HbA_1c is under 7%. The average HbA_1c in these patients during pregnancy was just 6.2%, and 83% of the patients in the study achieved tight glycemic control by ADA standards. It's widely assumed that such control would bring the risk of complications into line with the general population. The truth turned out to be very different.

The risk of congenital malformation in babies born to women in this study was 3.4 times higher than in the general population. Perinatal mortality was 3.5 times more likely, and macrosomia (high birthweight), a condition known to be associated with diabetic mothers, was 4.5 times more likely.

The most common complication in these babies was neonatal hypoglycemia, which occurred in no fewer than 64%. Most of these cases were quite severe, so the authors urge aggressive preventive management of this problem.

Though these figures are depressing, they didn't imply that glycemic control was pointless. The picture was clearly better in the patients with the best control although their complication rates were still much higher than in the general population; rates were lower among women in the planned pregnancies group. The authors suggest that's because more of these women took folate supplements.