Why health care professionals need to talk about the long-term impact of gestational diabetes.
Boyd E. Metzger, MD, is a co-author (with Dr. Thomas A. Buchanan) of the “Gestational Diabetes” chapter in Diabetes in America. Here he explains why everyone who provides health care to mothers and their children should be concerned about gestational diabetes.
Q: What do women’s health care providers need to know about gestational diabetes?
A: Gestational diabetes has increased in frequency, in parallel with increases in obesity and overweight, type 2 diabetes, impaired glucose tolerance, and impaired fasting glucose in the general population. About 25% of women of childbearing age, between the ages 18 and 40, now have pre-diabetes. Given that pregnancy is essentially a stress test for insulin resistance, it’s not surprising to see the increase in gestational diabetes.
From the original Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study, we know that there is a continuous association between a pregnant woman’s blood glucose levels and perinatal outcome risks. Blood glucose levels, even short of diabetes, of the mothers were associated with larger and/or fatter infants that are more likely to develop hypoglycemia and hyperinsulinemia. And now, having completed the HAPO Follow-Up Study (HAPO-FUS), we know that there is a continuous association between the mother’s blood glucose during pregnancy and the child’s risks of disordered glucose metabolism and adiposity.
Q: Tell us more about the perinatal risks of gestational diabetes.
A: The mother with gestational diabetes and her fetus have all the pregnancy-associated risks that somebody with pre-existing type 1 or type 2 diabetes has, such as high blood pressure, preterm birth, and large baby size necessitating Cesarean delivery. The magnitude of those risks is not as high—for example, the risk of pre-eclampsia is lower for women with gestational diabetes compared with women with type 1 diabetes, but it’s still double compared with the risk for women who don’t have gestational diabetes. It’s important to note that about 85 to 90% of all diabetes in pregnancy is gestational diabetes; other forms of diabetes, such as type 1 and type 2, account for the remainder. So cumulatively, gestational diabetes accounts for the vast majority of the birth complications.
In our chapter on gestational diabetes in Diabetes in America, we sort of emphasize the opposite point, and I think that’s fine, which is when you make a diagnosis of gestational diabetes, the majority of the mothers are going to have normal perinatal outcomes. If we treat everybody with the diagnosis the same—giving every woman with gestational diabetes extra ultrasounds, for example, or sending them all to high-risk obstetrics practices—we are, in a sense, overtreating. The more we can identify those women with gestational diabetes who can be successfully managed without higher-intensity treatment, the better. There’s an important lesson to be learned from the randomized trials of women with mild gestational diabetes, which found that treatment with a specific diet and exercise can improve outcomes. Less than 20% needed insulin.
Q: What about after the birth—do the risks continue?
A: Women who develop gestational diabetes while pregnant have an increased risk of developing type 2 diabetes later in life. They are also at risk for a recurrence of gestational diabetes in later pregnancy, with all its potential problems.
Q: Should health care providers who are not diabetes specialists address this topic with their patients?
A: Yes. Most care is being provided in the primary care setting, and health care providers need to know that they have many, many patients at increased risk for diabetes, whether it’s due to previous gestational diabetes, family history of diabetes, being a member of an ethnic group at higher risk for diabetes, or being overweight. Diabetes prevention should be one of the major topics in primary care in the same way that cardiovascular disease prevention is a major responsibility. And, of course, the combination of diabetes and cardiovascular disease is a very big one.
Providers need to raise the topic with their female patients because some women with previous gestational diabetes don’t always remember that they had it. And for some women, once their blood glucose levels go down again after the delivery, they are reassured and don’t retain the fact that the risks of gestational diabetes are long-term.
Q: Once the topic is raised, what else should be done?
A: Women with gestational diabetes should be re-evaluated for diabetes within a reasonable postpartum period. This has been a standard recommendation for decades, but it’s often missed.
For women who are on Medicaid-type assistance during their pregnancy, they lose that benefit about 6 weeks or so after delivery. Ideally, they will be re-evaluated at a postpartum visit with their obstetrician, but that often doesn’t happen, and then they have no more covered health care visits. Women with regular insurance don’t have that time limit, but even so, the re-evaluation is often not accomplished. This happens for many reasons, one being that the mother’s own health care issues often don’t stay front and center because taking care of the new baby and any other children is so time-consuming.
If we could somehow build evaluation of the mother into pediatric visits, that would be helpful. There are multiple standard times when infants are seen by their health care providers in the first year of life. But pediatricians aren’t prepared for doing glucose checks on the mother, because we provide care in silos. Yet it is a family issue. So, if we—meaning all of us health care providers including pediatricians—if we continually emphasize diabetes prevention, that may help.
We don’t know at this point whether our treatment of gestational diabetes will lower the long-term metabolic and overweight/obesity risk for children, but knowing that such children are at risk, like their mothers, maybe that will help. For instance, the child’s doctor may monitor growth charts more closely with knowledge of this fact as part of the child’s health history.
As we develop more integrated electronic health record systems, all the information about a person ought to be available easily by reviewing the record. This would make it easier for health care providers to learn about and follow up on a history of gestational diabetes. But our records systems aren’t quite there yet.
Q: How can women with a history of gestational diabetes prevent or delay development of type 2 diabetes?
A: We certainly know from the Diabetes Prevention Program (DPP) Study and its follow-up study, the DPP Outcomes Study, that women with a history of gestational diabetes, just like others with diabetes risk factors, respond to metformin and lifestyle changes—primarily increasing physical activity and dietary changes to achieve some weight loss. In the study, we saw with these women a very substantial reduction in progression to type 2 diabetes. The success of these interventions has been reproduced in many studies, for all people at risk of diabetes including women with a history of gestational diabetes.
Q: Can lifestyle counseling help?
A: It certainly works. Lifestyle counseling was provided in the original DPP Study and has been translated into other models. For example, the YMCA has been successful in doing this even though the counselors are trained lay people, not medical professionals. [The YMCA program is based on the National Diabetes Prevention Program of the Centers for Disease Control and Prevention.