Gestational diabetes: Optimizing Dx and management in primary care

Women diagnosed with prediabetes in 1 study were found to have significantly less weight gain during pregnancy compared with patients with normal A1C, suggesting a benefit in early identification and intervention.

While there are no current guidelines for treating prediabetes in pregnancy, women diagnosed with prediabetes in 1 study were found to have significantly less weight gain during pregnancy compared with patients with normal A1C,¹² suggesting there may be a benefit in early identification and intervention, although further research is needed.¹¹ In a separate case-control study (n = 345 women with GDM; n = 800 control), high rates of gestational weight gain (> 0.41 kg/wk) were associated with an increased risk of GDM (odds ratio [OR] = 1.74; 95% CI, 1.16-2.60) compared with women with the lowest rate of gestational weight gain (0.27-0.4 kg/wk [OR = 1.43; 95% CI, 0.96-2.14]).¹³ Thus, it is helpful to have proactive conversations about family planning and adequate weight and glycemic control with high-risk patients to prepare for a healthy pregnancy.

Obesity and weight management. Patients who are overweight (body mass index [BMI], 25-29.9) or obese (BMI > 30) have a substantially increased risk of GDM (adjusted OR = 1.44; 95% CI, 1.04-1.81), as seen in a retrospective cohort study of 1951 pregnant Malaysian women.¹⁴ Several factors have been found to contribute to successful weight control, including calorie prescription, a structured meal plan, high physical activity goals (60-90 min/d), daily weighing and monitoring of food intake, behavior therapy, and continued patient–­provider contact.¹⁵

Most obstetricians use a 2-step method to screen for GDM with an initial 75-g oral glucose tolerance test, followed by a 50-g glucose load test if needed.

The safety, efficacy, and sustainability of weight loss with various dietary plans have been studied in individuals who are overweight and obese.¹⁶ Ultimately, energy expenditure must be greater than energy intake to promote weight loss. Conventional diets with continuous energy restriction (ie, low-fat, low-carbohydrate, and high-protein diets) have proven to be effective for short-term weight loss but data on long-term weight maintenance are limited.¹⁶ The Mediterranean diet, which is comprised mostly of vegetables, fruits, legumes, fish, and grains—with a lower intake of meat and dairy—may reduce gestational weight gain and risk of GDM as suggested by a randomized controlled trial (RCT; n = 1252).¹⁷ Although the choice of diet is up to the patient, it is important to be aware of different diets or refer the patient to a registered dietician who can help the patient if needed.

Reduce risk with adequate weight and glycemic control

Prevention of GDM during pregnancy should focus on weight maintenance and optimal glycemic control. Two systematic reviews, one with 8 RCTs (n = 1792) and another with 5 studies (n = 539), assessed the efficacy and safety of energy-restricted dietary intervention on GDM prevention.¹⁸ The first review found a significant reduction in gestational weight gain and improved glycemic control without increased risk of adverse maternal and fetal outcomes.¹⁸ The second review showed no clear difference between energy-restricted and non–energy-restricted diets on outcomes such as preeclampsia, gestational weight gain, large for gestational age, and macrosomia.¹⁸ These data suggest that while energy-restricted dietary interventions made no difference on maternal and fetal complications, they may still be safely used in pregnancy to reduce gestational weight gain and improve glycemic control.¹⁸

Once a woman is pregnant, it becomes difficult to lose weight because additional calories are needed to support a growing fetus. It is recommended that patients with healthy pregestational BMI consume an extra 200 to 300 calories/d after the first trimester. However, extra caloric intake in a woman with obesity who is pregnant leads to metabolic impairment and increased risk of diabetes for both the mother and fetus.¹⁹ Therefore, it is recommended that patients with obese pregestational BMI not consume additional calories because excess maternal fat is sufficient to support the energy needs of the growing fetus.¹⁹

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