Fruit of the Womb
Fruit of the Womb

Diabetes in Pregnancy -6 - Diet and Exercise as the Foundation for Management of GDM

Once we have established the diagnosis of gestational diabetes mellitus (GDM), the first step in management is to counsel the patient regarding the diagnosis, management options, potential risks to the pregnancy, antepartum assessment of the baby, and the importance of postpartum follow-up. All that said and done, there are about as many different ways to manage a gestational diabetic as there are Maternal-Fetal Medicine specialists in the U.S. Part of the reason for disparities in recommendations for care reside in skepticism regarding benefits to outcome, i.e., does aggressive management really decrease risks for fetal macrosomia, compromise in utero, shoulder dystocia and brachial plexus injury at delivery, or even cesarean delivery. Quite frankly, I have adopted the attitude that those issues may be important, but are not, necessarily, the most significant ones! Usually as late in the pregnancy as the diagnosis of GDM is made and therapy implemented, we will not significantly influence the occurrence of macrosomia. Similarly, it is the rare pregnancy with GDM in which respectable blood sugar control is established that will result in a fetal death in utero. And, since cesarean delivery rates around the country are almost uniformly above 30%, patients with GDM, even if they all underwent cesarean delivery (which is truly unnecessary), that would not add significantly to the problem!

The issues that concern me more are related to long-term care of the mother and short- and long-term outcomes for the baby. Due to the motivation to have a ‘healthy baby’ (and to be around to see her grandchildren!), pregnancy is about as good a time as we will ever have to provide information to the mother that may reduce her own future risks of diabetes and its attendant complications (e.g., hyperlipidemia, hypertension, cardiovascular disease, shortened lifespan). From the baby’s standpoint, complications related to hyperinsulinemia, hypoglycemia, hyperbilirubinemia, and respiratory distress in the newborn as a consequence of poor maternal blood glucose control can be significant, especially if the baby is delivered at an institution that is not in the mode to rapidly identify these complications or to manage them aggressively should the need arise. Furthermore, there is growing evidence that maternal hyperglycemia affects the long-term risks for the baby with regard to obesity, lipid profiles, cardiovascular disease and diabetes by a mechanism of in utero epigenetic ‘programming’ (a good subject for another series of posts). So, over time, I have generally taken a relatively aggressive approach to ongoing evaluation and therapy of GDM once the diagnosis is made.

The foundations of GDM management are diet and nutritional counseling, glucose monitoring, modest exercise, and medical therapy if the first three do not result in normalization of blood sugars. It is estimated that about 70% of GDM can be managed without medical therapy if attention is paid to the first three (Brody, et al., Obstet Gynecol 2003;101:380-92) and quite frankly, education and life-style modification in these areas will provide the most benefit to the mother for her long-term health if she is willing to accept responsibility for the same. Although almost everyone agrees in principle on the importance of these measures, there is no standard algorithm for care and, indeed, to some extent the care should be individualized to the patient. That does not mean we should ever lessen our desired standards for, or underestimate the patient’s willingness and ability to achieve, good glycemic control, but sometimes we may have to ‘bend the rules’ a bit to get to that point!

My first steps in counseling the newly identified woman with GDM is to review her past medical and obstetrical history and her current obstetrical course, explain in very general terms what diabetes is and the pregnancy/neonatal concerns, emphasizing at the outset the value of tight blood sugar control, assess her lifestyle and habits that might influence (for better or worse) her diabetic management, and explain that what she learns today, and over the remaining months of the pregnancy, may be important for the rest of her life. Prior to counseling about diet and nutrition, I try to pin down how much weight she has gained since conception. There are several reasons for this: If weight gain has been appropriate for her body habitus, then her caloric intake is probably appropriate and dietary counseling will focus on redistribution of caloric intake during the day and type of foods being eaten. If weight gain has been excessive, then counseling will emphasize not only the preceding points, but overall reduction in caloric intake as well. And, if she has had poor weight gain, and still has GDM, she is more likely to be a pregestational diabetic, or to be highly insulin-resistant, and require more than just dietary counseling alone. I have found that some women (unfortunately, often the most overweight) are absolutely terrified by what they may perceive as “dieting” during pregnancy, and the difference between ‘dieting’ and ‘good nutrition’ must be clearly explained. In most circumstances, they are also reassured that they will be expected (given ‘permission’) to continue to gain weight during the rest of their pregnancy – the actual amount determined by habitus. Indeed, in certain situations I have been known to tell extremely obese women that they may safely either gain no more weight, or actually lose weight during the last few months of pregnancy and, if done correctly, this should have no ill effects on their babies.

The next step in counseling is to explain the broader concepts of diet and nutrition (reserving the specifics for a visit to the dietitian). We place most of our patients on ‘3 meals and 3 snacks’ throughout the day – redistributing their total caloric intake. Patients are told that this approach, accompanied by adjustment of the type of calories they are ingesting, will curb their appetite and help to avoid wild swings in their blood glucose levels that might lead to abandoning their ‘diet’ for ‘comfort foods’. I also usually take this opportunity to explain that the baby basically ‘eats’ constantly, is constantly removing glucose from the maternal circulation in a manner reflecting maternal blood sugar levels, are ‘bottomless wells’ as far as blood sugar is concerned, and have the ability to make as much insulin as they need to use what they get, thereby leading to the problems related to excessive growth, too much insulin production, and low blood sugars after they are delivered (and no longer have the maternal ‘Willy Wonka Factory’ at their unlimited disposal).

The next part of the discussion revolves around the total amount and type of calories to be consumed. This will vary depending on weight gain to that point and expected for the pregnancy, maternal habitus, and general level of daily activity. In this regard, I am a firm believer in the general approach recommended by Jovanovic-Peterson over the years: 30 kcal/kg for women at 80-120% of their ideal body weight; 24 kcal/kg for overweight women; and 12 kcal/kg for morbidly obese women. Patients are told that these levels are at thresholds that will usually avoid ketonuria and are just a “place to start” and will be adjusted based on weight gain and glycemic control. They are also asked (and given instructions on how) to distribute calories as no more than 40% carbohydrate and about 20% protein and 40% fat; and they are asked to replace simple sugars with more complex carbohydrates. An alternative approach is to simply “count carbohydrates” but I usually leave this to the dietitian to explain. As an adjunct to these recommendations, I usually make it clear that we are asking that they should minimize intake of specific foods/drinks, especially candy, soft drinks, “sweet tea” (a mainstay of our South Carolina population), high sucrose/fructose juices, and sources of excessive caffeine. (In reality, the ‘caveman diet’ of lean meats, fish, nuts, vegetables, and fruit, avoiding dairy products, cereals, and refined fat and sugar would probably be ideal for many pregnant women with or without GDM).

As part of their dietary regimen, I also recommend to those that don’t that they begin a modest exercise program – suggesting to the ‘novices’ in this arena, simply walking 30-60 minutes 3 or more times per week. One incentive I use to promote these lifestyle changes (other than that it is just plain good for them and their babies) is that these efforts may reduce their need for medications, especially the dreaded INSULIN, to control their diabetes during (and, perhaps, after) pregnancy. In closing this part of the discussion, I like to make sure that they understand we are not asking them, nor is it good for them or their babies (and we will know if they are doing it), to STARVE themselves to achieve normal blood sugar levels.

I guess we should stop at this point, having spent more time on this part of the discussion than anticipated, but it truly is the foundation for GDM management and, as such, deserved the attention! Anyway, we will continue our discussion of the other components of GDM management with our next post in this series…And by the way, HAPPY NEW YEAR!!!!
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