Low glucose most likely in early diabetic pregnancy

NEW YORK (Reuters Health) - Among pregnant women with type 1 diabetes, the incidence of mild or severe declines in blood glucose (hypoglycemia) is highest in early pregnancy, and metabolic control tends to be tighter in the last part of pregnancy, according to results of a study published in the journal Diabetes Care.

While optimal glycemic control is crucial for pregnant women with diabetes, the authors note, striving for normal glucose levels increases the risk of developing severe hypoglycemia, "the major limiting factor for achieving optimal blood glucose control in pregnant women with type 1 diabetes."

Dr. Lene Ringholm Nielsen, of Copenhagen University Hospital Rigshospitalet, Denmark, and colleagues evaluated the incidence hypoglycemia during different parts of pregnancy in 108 consecutive pregnant women with type 1 diabetes, with the aim of finding ways to develop ways of reducing the severity and frequency of the problem.

The patients monitored their plasma glucose 8 times a day for 3 days at week 8, 14, 21, 27 and 33 of pregnancy. They also completed a questionnaire regarding nausea, vomiting, hypoglycemia awareness, and history of mild or severe hypoglycemia.

Mild hypoglycemia was defined as low glucose levels that could be managed by the patients, and severe hypoglycemia as low glucose levels that required assistance from others.

Overall, 49 women (45 percent) experienced 178 severe hypoglycemic events during pregnancy. Of these events, 80 percent occurred before 20 weeks with a peak at 9 weeks.

The incidence of mild hypoglycemia was 5.5 events per patient per week in early pregnancy and significantly decreased as the pregnancy continued.

Overall, A1C levels, average blood glucose levels, and fluctuations in blood glucose decreased as the pregnancy continued, and there were no differences between women with and women without severe hypoglycemia.

Women who experienced severe hypoglycemia tended to report nausea or vomiting less frequently than women who did not experience severe hypoglycemia.

The results of further analysis revealed that previous episodes of severe hypoglycemia and poor awareness of hypoglycemia were independent predictors of developing severe hypoglycemia.

The investigators conclude that women who do not experience severe hypoglycemia before 20 weeks' of pregnancy are not likely to do so later, "enabling these women to strive for even stricter metabolic control in the last part of pregnancy."

SOURCE: Diabetes Care, January 2008.