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What are the problems with gestational diabetes treatment?
The two questions asked of any therapy are: “Is it safe?” and “Is it effective?” GD management is neither.
GD treatment per se has never been shown to have benefits. In fact, it is virtually untested. The first and only random assignment trial, the standard for determining care because this design eliminates many sources of bias and ensures similar groups, was published in 1997. It concluded that intensive treatment offered no advantages over advising women to eat healthy (16). Meanwhile, several studies have found that identification as a gestational diabetic in and of itself substantially increases the odds of cesarean section (3,19,38,50).
Individual components of GD protocols also fail the safety/effectiveness test:
-- Diet or diet plus insulin therapy: The standard GD diet is a healthy diet. However, while it reduces blood glucose to normal range in most women, it has little or no effect on birth weight (54). Many women, though, are prescribed limited calorie diets. Reducing calorie intake by more than one-third causes the body to switch to a starvation metabolism (ketosis) that produces byproducts known to be harmful to the baby (31). Limiting food intake can also lead to malnutrition (27). Aggressive insulin use can cause underweight babies and symptomatic episodes of low blood sugar (hypoglycemia) (3,32). A Guide to Effective Care in Pregnancy and Childbirth lists both diet treatment and diet plus insulin treatment under “Forms of Care Unlikely to be Beneficial (12).”
-- Tests of fetal well-being: Of the four random assignment trials of nonstress testing, the most commonly used fetal surveillance test, none found any benefit for testing, although they were in populations of women at moderate to high risk (41). All tests of well-being have high false-positive rates, meaning the test says there is a problem when there isn’t. This leads to unnecessary inductions and cesareans with all their attendant risks.
-- Fetal weight estimates: Ultrasound predictions that the baby will weigh over 4,000 grams are wrong one-third to one-half of the time (6,9,14,20,33,56). As with fetal well-being tests, the belief that the baby is big leads to unnecessary inductions and cesareans. Two studies showed that when obstetricians believed, based on ultrasound, that women were carrying babies weighing over 4,000 grams, half had cesareans, versus less than one-third of women not thought to have babies this big, but who actually did (35,56).
-- Induction of labor or planned cesarean: Many doctors induce labor in the belief it averts cesareans due to big babies. Some think induction or planned cesarean prevents shoulder dystocia (the head is born, but the shoulders hang up). Studies of induction and planned cesarean for suspected big baby show no benefits for either practice (6,9,14,20,33,49,56).
-- Monitoring newborn blood sugar: The reasoning behind this is that if the mother has high blood-sugar levels, the baby will produce extra insulin. After birth, this excess insulin can cause low blood sugar. No studies have tested whether checking the blood sugar of a baby who shows no symptoms of low blood sugar has any value. However, test results can lead to the baby being given a bottle of sugar water or formula, which interferes with establishing breastfeeding, separation from the mother for observation in the nursery, or both.
Finally, treatment also fails to prevent increased incidence of preeclampsia, impaired glucose tolerance in children, and childhood overweight (42,44-45,53).
Another rationale given for diagnosing and treating gestational diabetics is identifying women at risk for developing Type II diabetes. However, predicting who is likely to develop diabetes can be done equally well on the basis of race, ethnicity, and weight.
Curiously, while several prominent GD researchers and experts acknowledge the lack of sound data supporting their recommendations, none have backed off (1,26,37,39). These experts devise GD guidelines for practicing doctors and midwives, most of whom have no idea how shaky the GD edifice is. Even those who doubt the value of screening all or most women for GD may have little choice if testing and treatment is the community standard of care.