NEW YORK (Reuters Health) – Pregnant women with type 1 diabetes had fewer severe hypoglycemic episodes when they started a preprandial insulin analog regimen before conception rather than afterward.

This finding is from an exploratory analysis of data from a large randomized trial that compared maternal and fetal outcomes with insulin aspart versus human insulin, each administered before every meal. The study investigators enrolled 322 diabetic women who were either pregnant or planning to become pregnant.

In the earlier trial, insulin aspart tended to be more effective at improving postprandial glucose control and preventing hypoglycemia.

After the study was completed, Dr. Simon Heller, from Northern General Hospital, Sheffield, UK, and colleagues looked at whether patterns of hypoglycemia differed depending on when the women were enrolled.

As they report in the December 10th online issue of Diabetes Care, 99 women were randomized before conception. The others were randomized during the first trimester.

Severe hypoglycemia was defined as an event that required outside assistance associated with a plasma glucose level of less than 3.1 mmol/L, reversal of symptoms after food/glucagon/IV glucose, or both.

The overall prevalence of severe hypoglycemia was 23% and, consistent with previous reports, events were most common in early pregnancy.

During the first half of pregnancy, women who were randomized before conception were 70% less likely to experience severe hypoglycemia than those randomized in early pregnancy. During the second half of pregnancy, randomization before conception cut the risk by 35%. These associations, however, did not reach statistical significance.

“While the relative risks in women randomized pre-conception are not statistically significant due to lack of power, the marked trend to lower rates in this group is of interest,” the authors state.

As for the optimal type of insulin for preprandial therapy, there was a trend toward lower rates of severe hypoglycemia with insulin aspart at all points studied.

“While the limitations of exploratory analyses prevent any firm conclusions, these data suggest another potential advantage of prenatal care that is worthy of further investigation,” the authors conclude.

Diabetes Care 2009.