BACKGROUND & AIM: In the United States, approximately 4% of pregnant women have diabetes. Of these, 88% have gestational diabetes mellitus (GDM) and the remaining have pre-existing diabetes type 1 or 2. The risk factors for developing GDM are marked obesity, previous personal history of GDM, glucose intolerance and a strong family history of type 2 diabetes.
Diabetes in pregnancy is characterized by increased insulin secretion but a decreased response to its action. This ‘insulin resistance’ is due to the placental secretion of hormones which act to ensure that the foetus has an adequate supply of glucose. The risk factors for a diabetic pregnancy include an increased incidence of developmental abnormalities for the foetus and miscarriages in women with poor glycemic control.
The aim of this review was to evaluate the current evidence in diabetes management to improve outcomes in diabetic pregnancies.
RESULTS: Diabetic women need to normalize blood glucose concentrations when planning pregnancy and in early pregnancy to reduce the risk of miscarriages. Self-monitoring of blood glucose is mandatory during pregnancy, especially for patients with type 1 diabetes. Poor glycemic control leads to increased maternal-foetal transfer of glucose and amino acids as well as hyperinsulinemia in the foetus. These metabolic changes contribute to the development of macrosomia and can lead to difficult delivery, an increased rate of caesarean section, and an increase in foetal morbidity as well as maternal hypertension and preeclampsia.
An initial step to address the diabetes is medical nutrition therapy which not only takes into account the total daily caloric intake and its carbohydrate content, but also the number of meals throughout the day. Restriction of carbohydrate to 35–40% of calories has been shown to decrease maternal glucose levels and improve maternal and foetal outcomes.
In women without medical or obstetrical contraindications a program of moderate exercise such as walking, stationary bicycling, low-impact aerobics, and swimming is recommended. Each exercise session should begin with a 5- to 10-minute warm-up period involving some flexibility exercises (stretching) to reduce the risk of musculoskeletal injury during the workout, followed by a cool-down period. Exercise increases insulin sensitivity of muscle glucose transport and also enhances insulin action. Programs of moderate physical exercise have been shown to lower maternal glucose concentrations in women with GDM.
For existing diabetic patients, insulin requirements vary during pregnancy. Type 1 patients may need to progress to 1.0 units/kg over time whilst pregnant type 2 diabetic patients may need higher doses (1–2 units/kg) from the onset to deal with insulin resistance and the requirements of the pregnancy.
When diet and exercise are unable to maintain glucose levels within the normal range, the use of sulfonylureas and biguanides may also be beneficial.
CONCLUSIONS: Diabetic pregnant women should plan their pregnancy, maintain good metabolic control of their diabetes and exercise. An interdisciplinary team approach with centralized care offers the best outcomes.
Clinical Diabetes, 2005; 23(4):165-68