Diabetes Mellitus

Diabetes Mellitus

Pregnancy is associated with increased tissue resistance to insulin, resulting in increased levels of blood insulin as well as glucose and triglycerides. These changes are due to placental lactogen and elevated circulating estrogens and progesterone. Although pregnancy does not appear to alter the long-term consequences of diabetes, retinopathy and nephropathy may first appear or become worse during pregnancy. Debate continues over whether gestational diabetics are women whose glucose intolerance is solely a function of their pregnant compared with their nonpregnant state. Alternatively, pregnancy may merely serve to unmask an underlying propensity for glucose intolerance, which will be evident even in the nonpregnant state at some time in the future if not in the immediate postpartum period. However, goals for glycemic control during pregnancy are the same whether the diagnosis is made before or during the pregnancy.

Prepregnancy counseling and evaluation of diabetic women should include a complete chemistry panel, HbA1c determination, 24-hour urine collection for total protein and creatinine clearance, funduscopic examination, and an ECG. Any medical problems should be addressed, and HbA1c levels of less than 8% should be achieved before pregnancy. Euglycemia should be established before conception and maintained during pregnancy with daily home glucose monitoring by the patient. A well-planned dietary program is a key component, with an intake of 1800-2200 kcal/d divided into three meals and three snacks. Insulin is given subcutaneously in a split-dose regimen with frequent dosage adjustments. Patients taking oral agents prior to pregnancy should be switched to insulin. However, limited information suggests that agents such as glyburide may be safe and effective in pregnancy. The use of continuous insulin pump therapy has been found to be very useful during pregnancy in women with type 1 diabetes mellitus.

Congenital anomalies result from hyperglycemia during the first 4-8 weeks of pregnancy. They occur in 4-10% of diabetic pregnancies (two to three times the rate in nondiabetic pregnancies). Euglycemia in the early weeks of pregnancy, when organogenesis is occurring, reduces the rate of anomalies to near-normal levels. Even so, because few women with diabetes begin a rigorous program to achieve euglycemia until well after they have become pregnant, congenital anomalies are the principal cause of perinatal fetal deaths in diabetic pregnancies. All women with diabetes should receive counseling about pregnancy and, when the decision has been made to start a family, should receive prepregnancy management by physicians experienced in diabetic pregnancies.

Fasting and preprandial glucose values are lower during pregnancy in both diabetic and nondiabetic women. Euglycemia is considered to be 60-80 mg/dL while fasting and 30-45 minutes before meals and < 120 mg/dL 2 hours after meals. This is the target for good diabetic control during pregnancy. Glycated hemoglobin levels help determine the quality of glucose control both before and during pregnancy.