The correct answer is D. This pregnant patient may have gestational diabetes. Her one-hour 50-g oral glucose tolerance test (OGTT) was abnormal with a value > 140 mg/dL. Her fasting blood glucose is < 125 mg/dL, so she does not have overt diabetes, but it is important to determine if she has impaired glucose tolerance or gestational diabetes by performing the 3-hour 100-g OGTT. Normal values after a 100-g glucose load are:
- One hour: < 180 mg/dL
- Two hours: < 155 mg/dL
- Three hours: < 140 mg/dL
If the fasting glucose is > 90 mg/dL, but the other values are normal, then she has impaired glucose tolerance. If ≥ 2 values are abnormal (including fasting glucose), then the diagnosis of gestational diabetes is established. This patient has at least one common risk factor for gestational diabetes: obesity. Other risk factors a personal history of impaired glucose tolerance or gestational diabetes, being a member of an ethnic group with high prevalence of type 2 diabetes, > 30 years of age, family history of diabetes, and previous birth of an infant > 4,000 g. Diligent efforts to achieve euglycemia for this patient may prevent preeclampsia and gestational hypertension in this pregnancy as well as labor-related morbidity for the fetus and mother due to macrosomia.
Insulin therapy (choice A) might be considered if home glucose monitoring (4 times daily) reveals persistent hyperglycemia despite diet and exercise changes. Insulin is generally preferred over oral medications in the treatment of gestational diabetes.
Oral antihyperglycemic medications (choice B), specifically metformin or glyburide, might be considered if home glucose monitoring (4 times daily) reveals persistent hyperglycemia despite diet and exercise changes. In patients that are unable or unwilling to comply with insulin therapy, this is a reasonable alternative.
Obtaining hemoglobin A1c, determining renal function, ruling out proliferative retinopathy and establishing home blood glucose monitoring (choice C) would be important if the patient was diabetic prior to pregnancy, or if she was diagnosed with overt diabetes based on a fasting blood glucose ≥ 125 mg/dL, in which case the 3-hour OGTT would not have been performed.
Providing diet education and establishing home blood glucose monitoring (choice E) will be important once the correct diagnosis is established. Exercise, if there are no medical or obstetrical contraindications, is also encouraged.