Gestational Diabetes
What is Gestational Diabetes (GDM) ?
Gestational diabetes mellitus is diabetes that begins or is first recognized during pregnancy. It is common, affecting about 2-5 % of pregnant women.
What is diabetes ?
To answer this, recall that all cells in our body need glucose to function. This glucose comes from the carbohydrates we eat or from our own metabolism. Either way, we use insulin to get glucose from the bloodstream into the cell. If this system is not working, the bloodstream carries too much glucose, and the cells are starving. This is the essence of diabetes.
All pregnant women are relatively more carbohydrate intolerant than non pregnant women. However, if the problem gets to a certain extent, it causes complications for mother and baby.
What are the complications of GDM ?
Patients with GDM are at higher risk for hypertensive disorders like preeclampsia, excessively large babies, problems with delivery, and C section. Their babies are prone to lower blood sugar at birth, because they have been accustomed to mom's high blood sugar levels. They are prone to hyperbilirubinemia requiring "lights" (phototherapy) . In my experience, a patient does not need to be very far out of control for these complications to set in, so good control is strongly emphasized.
Who is at risk for Gestational Diabetes ?
The risk factors for gestational diabetes are older age, ethnicity, obesity, family history of diabetes, and past obstetric history of gestational diabetes. High risk ethnic groups are Hispanic, African, Native American, South or East Asian, or Pacific Islands ancestry .
How is GDM diagnosed ?
Most commonly, around 24-28 weeks, we use a sweet drink with a very precise amount of sugar in it. It is called the " Glucola test" . It is a 50-g, 1-hour glucose challenge to your system to see of you will metabolize it normally. You drink it ( I recommend chilled ) in the morning after a fast and then precisely one hour later, your blood is tested for it's glucose, or blood sugar, level. The use of jelly beans instead of a Glucola has been shown to be better tolerated, but this method has poor sensitivity (40%) when compared with Glucola (79%). You pass if your blood sugar (BS) is 130 mg/dl or less.
f you fail your Glucola test, you go on to a three hour glucose challenge test which is a whole morning full of fun. As the name suggests, you again fast, then come in for a fasting BS level, a 1hour, a 2 hour, and a 3 hour. If you fail one, you are probably a little carbohydrate intolerant and may be at increased risk for a large baby, but if you fail two values, you are a gestational diabetic. If your Glucola result is 200 mg/dl or greater, you have GDM. You don't even need to bother with the 3 hour challenge.
How is it treated ?
Ideally it is treated with a multi-pronged approach.
Diet
It is necessary and beneficial to adopt a diabetic diet. Happily, is a very pleasant diet to be on. And while I think what I am about to say would be considered heresy in the hallowed halls of medicine, I will say it anyway. The diabetic diet bears a certain resemblance to the very trendy and inappropriately named "Paleo" diet. This is so because it focuses a great deal on the protein component of meals, and fills in the rest of the volume, calories and nutrients with fruits and vegetables , not so much with grains, legumes (peas beans) or refined foods.
On the diabetic diet, one develops not only an awareness of the carbohydrate (CHO) content of foods, but also their glycemic index. The glycemic index describes how fast the digested food releases sugar into the bloodstream. This is of critical importance and somewhat underemphasized in diabetic teaching. One learns also how the timing of meals and snacks as well and the combinations of foods within a given meal or snack affects the blood sugar, as well as how the patient feels and performs.
In summary, knowledge of the diabetic diet comprises the following:
- CHO - absolute amount in meals and snacks
- Glycemic index of foods
- Timing of meals and snacks for even BS throughout the day and night
- Combinations of Proteins, Fats and CHO within meals for beneficial effects on glycemic index of the whole
- Choice of proteins, fats and CHO for highest nutritional value
To learn more, please see Nutrition in Pregnancy.
Exercise
Exercise in pregnancy is recommended for all but the most high risk and specifically complicated obstetric patients. Please see our section on Exercise in Pregnancy for more details. Gestational diabetes is not a contraindication to exercise. Exercise not only burns calories while you are doing it, but more importantly it raises your baseline metabolic rate so you burn more calories all the time. Exercise also burns fat. Finally, exercise builds muscle and muscle has a higher metabolic rate than fat ( Muscle burns fat).
It is worth noting that you will only build muscle, burn fat and increase metabolism if you are taking in enough calories in the first place. It sounds like a paradox, but you have to feed the fire. Diabetic management allows you to metabolize the food you take in. The whole problem with diabetes is that the calories you take in cannot get into the cell to be used for energy. Without diabetic treatment, excess blood glucose circulates in the bloodstream doing only harm, and eventually just getting deposited as fat.
As I mentioned in the section on the diabetic diet above, timing is key. This is also true with exercise as an adjunct to blood sugar control. In order to interpret the effects of dietary components and timing as well as daily exercise on your blood sugar levels throughout the day, the meals, snacks, and exersize need to be done at about the same time every day. This enables you to look back and analyze the day. If any blood sugar values are higher or lower than they should be, you can then rationally adjust them based on prior performance.
It is interesting to note that most of my patients who acquire a diagnosis of gestational diabetes are overweight to begin with and not accustomed to practicing good nutrition. Not uncommonly they eat very late in the day, infrequently and chose processed foods of very low quality. Is always interesting to hear what they say when they begin to follow a diabetic regimen. Not uncommonly they state two things: that this is a diet with very good (delicious and varied) food, and that they never realized how much they had to eat to keep their blood sugar stable and their metabolism high.
Oral agents like metformin (glyburide )
Sometimes when diet and exercise are both optimized, blood sugar levels are still out of range. At that point we add an oral (pill) medication called Metformin. It has an excellent safety profile before and during pregnancy. Before its use in gestational diabetes, it had been used in patients struggling with polycystic ovarian syndrome(PCO). If you review our pages on PCO, (aka Chronic Estrogenized Ovulation) you will recall that PCO has a mysterious component of carbohydrate intolerance. Of course when PCO patients do become pregnant, they are at higher risk for gestational diabetes.
Insulin injections
If diet, exercise, and metformin are insufficient to control blood sugars, the insulin is utilized. Insulin therapy is set up with the diabetic educators. Patients are taught how to measure insulin and self administer using insulin syringes. They test their BS several times a day and keep impeccable records on times and amounts of doses. This information goes alongside meal content and blood sugar values so a complete picture can be ascertained. In weekly visits, we review results and tailor the regimen. Most of my patients who needed insulin really dreaded it, but when it came down to using it, felt it was quite manageable. In my opinion, using insulin well is a matter of good timekeeping, record keeping, and measuring. Master these things and insulin therapy for GDM becomes safe and effective.
Postpartum
There's good news and bad news. The bad news is that once you have had gestational diabetes, you are at increased risk for diabetes outside of pregnancy the rest of your life. The good news is that if you were successful with your diabetic diet, physical activity, and restructuring of your day in pregnancy, and continue all this after baby is born, your weight and body composition will drift toward optimal without any additional effort. You can bring your risk down to baseline and enjoy your newfound health with your baby.
References:
CDC Pamphlet on Gestational Diabetes
ACOG Practice Bulletin Number 30, September 2001 Gestational Diabetes.