Diabetes NewsOctober 2010

Click here to return to previous page

Hypoglycemia in Type 1 Diabetic Pregnancy

Diabetes Care • March 2010

Severe hypoglycemia is common in pregnant women with type 1 diabetes, with observed rates up to 15 times those reported by the Diabetes Control and Complications Trial, and severe hypoglycemia occurs in 19-44% of patients treated with intensive insulin therapy during pregnancy. The risk of experiencing a severe event is usually highest in early pregnancy, particularly during the first trimester. The risk factors that predict hypoglycemic episodes during pregnancy include duration of diabetes, a history of severe episodes (recurrent events), hypoglycemic unawareness, a change in insulin treatment (such as regimen or dosing) or a high insulin dose and A1C < 6.5%. However, because normoglycemia is universally recommended in diabetic pregnancy with A1C levels between 4.0 and 6.0 percent advocated to optimize pregnancy outcome, minimizing the risk of severe hypoglycemia is a major challenge to those caring for pregnant women with type 1 diabetes.

Preconception care programs are associated with both reduced malformations and fewer early fetal loses in pregnant women with type 1 diabetes, perhaps due to improved glycemic control in the first stages of pregnancy. It is possible that working with women to improve metabolic control and optimize their insulin regimen the rate of severe episodes of hypoglycemia postconception, but this has yet to be demonstrated.

A randomized open label, parallel-group, multinational, multicenter study investigating maternal and fetal outcomes in 322 women with type 1 diabetes treated with either prandial insulin aspart (IAsp) or human insulin. IAsp was injected immediately before eating was as effective and well tolerated as human insulin administered 30 minutes before eating. This study supports the conclusions of trials in nonpregnant individuals with type 1 diabetes, which suggest that the advantages of rapid-acting insulin analogs are most likely to be seen in those with tight control.

The aim of this exploratory analysis was to compare the incidence of severe hypoglycemia during pregnancy between women enrolled into the trial either preconception or early in the first trimester. Finally, also compared were the effects of the different on rates of severe hypoglycemia according to the time of enrollment of (pregnant) women into the study.

Objective - A randomized trial compared prandial insulin aspart (IAsp) with human insulin in type 1 diabetic pregnancy. The aim of this exploratory analysis was to investigate the incidence of severe hypoglycemia during pregnancy and compare women enrolled preconception with women enrolled during early pregnancy.

Research Design and Methods - IAsp was administered immediately before each meal was compared with human insulin administered 30 minutes before each meal in 99 subjects randomly assigned preconception and in 223 subjects randomly assigned in early pregnancy. NPH was the basil insulin. Severe hypoglycemia (requiring third party assistance) was recorded prospectively preconception (where possible), during pregnancy and postpartum.

Results - The study includes the 99 of the 189 subjects making up the preconception group who became pregnant during the 12 months specified in the original protocol. Age, A1c, BMI and duration of diabetes were similar in subjects randomly assigned preconception or in early pregnancy and between treatment groups. Of the patients, 23% experienced severe hypoglycemia during pregnancy with the peak incidence in early pregnancy.

Conclusions - The data suggest that women enrolled in a clinical trial preconception experience fewer hypoglycemic episodes than those enrolled postconception. This exploratory analysis was based upon the data obtained from the largest controlled trial to date involving an insulin analog in the treatment of pregnant women with type 1 diabetes. Despite the limitations imposed by the observational design, the researchers believe that exploring the influence of the timing of entry into the trial on the risk of hypoglycemia is clinically relevant. The data suggests that women enrolled in a clinical trial preconception experience fewer hypoglycemia episodes than those enrolled postconception.

It is well known that severe hypoglycemia is common during pregnancy and is most likely to occur during the first trimester. One observation from the data is that the severe incidence of hypoglycemia does not peak in early pregnancy in women who are enrolled in preconception. This group had a low rate of severe hypoglycemic episodes compared to the 1.3 events per patient per year seen in the nonpregnant background population.

It is possible that patients who entered the trial preconception were more motivated and experienced in diabetes self-management than those enrolling in postconception, as represented by tighter control and less hypoglycemia. However, glycemic control (A1c and plasma glucose) was similar between those randomly assigned in early pregnancy and those randomly assigned postconception. An alternative explanation is that the extra professional input in the preconception period led to optimized insulin therapy and a lower risk of hypoglycemia. Although preconception counseling is associated with a reduced malformation rate in the offspring of women with type 1 diabetes, the researchers are unaware of previous studies studying the impact of preconception input on severe hypoglycemia during the ensuing pregnancy.

It is conceivable that subjects who changed their insulin regimen may have had higher rates of hypoglycemia than those who did not change their insulin regimens; however, the numbers of those taking the same insulin in the trial were too small to undertake formal conclusions. Nonetheless, switching to A1sp after human insulin treatment during pregnancy did not seem to worsen the risk of hypoglycemia, confirming the results of a smaller, earlier study.

The data show an apparent rise in hypoglycemia in the weeks immediately before birth. This finding might relate to a fall in insulin requirements in the immediate predelivery period. A further intriguing was that the benefit of a rapid-acting insulin analog (IAsp) associated with a lower risk of severe hypoglycemia than that with human insulin tended to be most pronounced with in women who were randomly assigned preconception. This result may be related to their experience with the use of insulin IAsp before the influence of the metabolic changes of pregnancy. The rate of severe hypoglycemia immediately postpartum was considered higher than that in the last half of pregnancy and was also higher than that seen in observational data in nonpregnant diabetic populations, suggesting that women should focus on reducing their postpartum insulin dose and returning to preconception glycemic control goals.

This analysis suggests that the initiation of insulin analog treatment Preconception as opposed to during early pregnancy results in a lower risk of severe hypoglycemia in women with type 1 diabetes. The reasons for this finding remain unclear but might include the influence of preconception planning. Although the limitations of exploratory analysis prevent any firm conclusions, these data suggest another potential advantage of prenatal care that is worthy of further investigation. The observation should also be taken into account in future clinical trials during pregnancy in women with type 1 diabetes.

Reprinted with permission from the American Diabetes Association