C.M. is a 36-year-old Spanish-speaking Mexican-American woman with a 3-year history of type 2 diabetes. She was seen in her primary physician’s office because of a missed menstrual period; a pregnancy test was positive.

Her past obstetrical history included five vaginal deliveries and six miscarriages. All of her previous pregnancies occurred before the diagnosis of diabetes. Her previous medical care was in Mexico. She was never told of any glucose problem during her pregnancies, and she does not know the birth weights of her children. At the time of referral, she was 8 weeks pregnant and taking glyburide 10 mg twice daily. She was checking her blood glucose once daily in the morning with typical readings between 180 and 220 mg/dl on a plasma-referenced meter. Family history was positive for diabetes in her mother.

Her height was 62 inches, and her weight was 198 lb. Other than mild acanthosis nigricans and obesity, her physical examination was normal. She had no retinopathy and no evidence of neuropathy. Her glycosylated hemoglobin (HbA1c) level was 10.5% (normal <6.0%), and an office capillary blood glucose 4 h after lunch was 201 mg/dl.

She was started on insulin immediately and her glyburide was discontinued. She began monitoring her glucose before and after each meal, making daily adjustments in insulin. She received nutrition education with an appropriate calorie intake plus an emphasis on frequent smaller meals and limited carbohydrate intake. Within 1 week, her plasma glucose values were in the target range for pregnancy, but in the following week she had a spontaneous miscarriage. After her miscarriage, she discontinued insulin on her own and resumed taking glyburide 10 mg twice daily.

1.  Is there a relationship between C.M.’s diabetes and her adverse obstetrical history?

2.  What should have been done before her recent pregnancy to increase the odds of a favorable outcome?

3.  What considerations affect the choice of therapy for her diabetes now?

In the past, most diabetic women who conceived had type 1 diabetes. Today, however, we see an increasing number of women who have preconception type 2 diabetes. One reason is the tendency for many women to delay pregnancy until a later age. Another important factor, however, is the increasing number of children and young adults, especially in minority groups, who are developing type 2 diabetes.1 

The presence of diabetes in a woman of childbearing years is a special challenge. Blood glucose control during the first 2 months of pregnancy is critical to normal organ development. Commonly, however, women do not seek medical attention until after this period of early fetal development. Many women do not yet realize they are pregnant during this important period, especially if the pregnancy is not planned, which is the situation in well over half of all pregnancies. For this reason, preconception counseling must be an important aspect of management in all diabetic women of childbearing years, regardless of whether there is an expressed desire to conceive.2,3 

Even though C.M.’s diabetes was diagnosed 3 years ago, the fact that she is already poorly controlled on maximal sulfonylurea treatment suggests a longer duration of diabetes. This supports the possibility that her poor obstetrical history may have been related to undiagnosed (and, therefore, uncontrolled) diabetes. Certainly during her most recent pregnancy, C.M. was poorly controlled during the critical period of organ development, possibly leading to an anomaly incompatible with fetal viability.

Comprehensive preconception counseling is now indicated for C.M. Oral diabetic medications have not been adequately studied for safety during pregnancy. Therefore, a woman who is taking oral medication and who wishes to conceive should be switched to insulin, and control should be established before she becomes pregnant. If C.M. plans another pregnancy or if she is not actively using birth control, she needs to resume insulin treatment.

Even patients whose diabetes is well controlled with diet and exercise are almost certain to require insulin during the later stages of gestation, when insulin resistance increases markedly. Preparing patients for this likelihood and teaching insulin administration as part of preconception counseling is advisable. Before pregnancy occurs is the ideal time to address any patient fears and misconceptions about insulin treatment.

For a woman of childbearing age who does not wish to become pregnant, choice of therapy can be important. Insulin resistance, almost universally present in type 2 diabetes, may be associated with decreased fertility. This is most clearly evident in polycystic ovary syndrome.4 Oral diabetic medications that reduce insulin resistance, such as metformin and thiazolidinediones,5 may also restore fertility. Thus, a previously infertile patient with type 2 diabetes may become unexpectedly pregnant after starting an insulin-sensitizing medication unless she is counseled regarding the need for birth control.

1.  Preconception counseling is important for all women with diabetes, type 1 or type 2, who are in their childbearing years, since many pregnancies are not planned and poor glucose control early in pregnancy is associated with a higher incidence of major congenital defects.

2.  Especially in minority populations, increasing numbers of women with type 2 diabetes who are treated with oral medications may be in their childbearing years. There are not adequate safety data to recommend the use of oral diabetic medications during pregnancy.

3.  Oral diabetic medications that reduce insulin resistance may increase fertility in women previously unable to conceive.

Diane M. Karl, MD, is medical director of diabetes services at Adventist Health and an assistant professor of clinical medicine at Oregon Health Sciences University in Portland, Ore.

Rosenbloom AL, Joe JR, Young RS, Winter RS: Emerging epidemic of type 2 diabetes in youth.
Diabetes Care
American Diabetes Association: Preconception care of women with diabetes (Position Statement).
Diabetes Care
23 (Suppl 1)
Kitzmiller JL, Buchanan TA, Kjos S, Combs CA, Ratner R: Preconception care of diabetes, congenital malformations, and spontaneous abortions (Technical Review).
Diabetes Care
Utiger RD: Insulin and the polycystic ovary syndrome.
N Engl J Med
Dunaif A, Scott D, Finegood D, Quintana B, Whitcomb R: The insulin sensitizing agent troglitazone improves metabolic and reproductive abnormalities in the polycystic ovary syndrome.
J Clin Endocrinol Metab