Current management of diabetic pregnancy
Unlike conventional therapy, intensive drug therapy plus self-monitoring diminishes adverse obstetric outcomes in all types of diabetes
Hypoglycemia after exercise can be a positive marker
I recommend 20 to 30 minutes of exercise 3 to 4 times weekly for gravidas with diabetes, provided they are willing and able to perform it, because it can improve post-prandial blood glucose levels and insulin sensitivity.12
Blood glucose should be measured after exercise, especially in women with type 1 diabetes.
Hypoglycemic reactions during and after exercise may be positive markers of improved insulin sensitivity. Low blood glucose necessitates adjustment of the insulin dose and carbohydrate intake. Extra monitoring is warranted after evening exercise, as glucose uptake increases for several hours after exercise and can cause nocturnal hypoglycemia.
Intensive therapy: Why, when, how
The healthy body secretes insulin over 24 hours independent of nutrient intake. Basal insulin secretion maintains metabolic homeostasis by preventing excessive hepatic glucose production and the mobilization of free fatty acids from adipose tissue stores. This also helps maintain protein balance. Insulin secretion increases several times in response to the ingestion of food.
Treatment or consequences
Langer O, Yogev Y, Most O, et al. Gestational diabetes: The consequences of not treating. Am J Obstet Gynecol. 2005;192;989-997.
When diabetic women receive adequate preconception care and counseling and achieve glycemic control, the rate of congenital anomalies declines to levels seen in the general population.69-72
On the other hand, maternal hyperglycemia and resultant fetal hyperinsulinemia are central to the pathophysiology of diabetic complications:
- type 1 and type 2 diabetes—congenital malformations
- all pregnancies compromised by diabetes—increased rates of deviant fetal growth (macrosomia and intrauterine growth restriction), neonatal metabolic, hematological and respiratory complications, birth trauma, stillbirth, cesarean delivery and intensive care admissions.
I tell patients, “Some improvement is better than none” I explain to my patients how pregnancy itself imposes risk, and why it is crucial to follow protocols and achieve glycemic control. I explain the maternal and fetal complications associated with various glucose thresholds, and the added risks of maternal age, body composition, disease severity, and so on.
However, I also stress that even some improvement in glucose control is better than no improvement.
Insulin dosage requires frequent adjustment
To determine the insulin dose needed to achieve glycemic control in pregnant gravidas, multiple blood glucose measurements are needed because insulin requirements steadily increase throughout pregnancy in women with pregestational diabetes.13-16 Jovanovic and Peterson13 quantified these increases as 0.7, 0.8, 0.9, and 1.0 U/kg per day in the first trimester and at weeks 18, 26, and 36, respectively.
Using memory-based reflectance meters to monitor blood glucose, my colleagues and I observed that insulin requirements during pregnancy in women with pregestational diabetes are triphasic (TABLE) and require frequent assessment with individualized adjustment of the insulin dose in each trimester.16 Women with type 2 diabetes require significantly higher doses of insulin each trimester, compared with women with type 1 diabetes.
In women with gestational diabetes, we observed a biphasic increase in insulin requirements17:
- Insulin requirements increased up to the 30th week of gestation, necessitating frequent dose adjustments.
- After 30 weeks, insulin requirements stabilized, requiring minimal or no dose adjustments. Insulin requirements for obese subjects were 0.9 U/kg per day, compared with 0.8 U/kg per day for nonobese women.
TABLE
Insulin requirements during pregnancy for women with pregestational diabetes
| INSULIN REQUIREMENT (UNITS/KG/DAY) | ||
|---|---|---|
| TRIMESTER | TYPE 1 DIABETES | TYPE 2 DIABETES |
| 1 | 0.86 | 0.86 |
| 2 | 0.95 | 1.18 |
| 3 | 1.19 | 1.62 |
| Insulin requirements vary with gestational diabetes | ||
When to start drugs
Most women with pregestational diabetes are treated with insulin prior to pregnancy. Thus, the main task during pregnancy is maintaining or improving glycemic control. In gestational diabetes, pharmacologic therapy (insulin or glyburide) is initiated only when regulation of the diet fails to achieve the desired level of glycemic control or when the disease is severe enough to mandate therapy.
Authorities disagree on the threshold of severity that necessitates pharmacologic intervention (glyburide or insulin). Some suggest a threshold of fasting plasma glucose of at least 95 mg/dL,18-20 which will decrease the rate of macrosomic and large-for-gestational-age infants,19,21 while others suggest at least 105 mg/dL.19,22
All authorities agree that drug therapy should be started when postprandial glucose levels are 120 mg/dL or higher at 2 hours or 140 mg/dL or higher at 1 hour.
