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CVD Risk History Predicts Gestational Diabetes

A woman’s cardiometabolic profile predicted the risk of gestational diabetes as early as seven years before pregnancy….

Measurements of serum glucose, body mass index (BMI), and prehypertension or hypertension had independent associations with gestational diabetes.

The combination of a BMI ≥25 and a glucose level of 100 to 140 mg/dL increased the risk of gestational diabetes by almost five-fold compared with women who had normal values for both measurements.

Obesity had the greatest impact among individual cardiometabolic risk factors. “In a multivariate model, pregravid hyperglycemia was a stronger predictor of subsequent gestational diabetes than overweight/obesity,” Monique M. Hedderson, PhD, of Kaiser Permanente Northern California in Oakland, wrote in the discussion of their findings.

“However, among gestational diabetes cases, only 9% of the women had pregravid mild hyperglycemia, whereas 44% were overweight or obese and only 4% had both, which suggests that, although glucose is a slightly strong risk factor, overweight/obesity is a much more prevalent exposure among gestational diabetes cases.”

Several well-established risk factors for gestational diabetes have been identified, including older maternal age, obesity, nonwhite race/ethnicity, previous macrosomic infant, and a family history of diabetes. However, as many as half of women who develop gestational diabetes do not have any of the risk factors, Hedderson and co-authors noted.

A better understanding of pregravid risk factors might aid identification of women with an increased risk of gestational diabetes and target them for risk-reducing interventions. Toward that end, investigators examined records of 199 women who developed gestational diabetes and 381 age-matched women who did not have diabetes during pregnancy.

The study population consisted of women who participated in a multiphasic health checkup during 1984 to 1996. The checkup included health questionnaires and measurements of blood pressure, height, weight, and random serum glucose and cholesterol tests.

Of 22,356 women who participated in the health maintenance program, 4,084 delivered babies during follow-up to 2005. The women with gestational diabetes and the control group were identified from the women who had deliveries during the study period.

For their analyses, the investigators used the following definitions:

  • Overweight/obesity: BMI ≥25 kg/m2
  • Prehypertension/hypertension: Blood pressure ≥120/80 mm Hg or use of antihypertensives
  • Hypercholesterolemia: Total cholesterol ≥200 mg/dL
  • Mild hyperglycemia: Pregravid serum glucose 100 to 140 mg/dL

The women had a mean age of 28 at the checkup and 35 at delivery. Whites accounted for 20% of the gestational diabetes cases, African Americans for 34%, Asians for 30.2%, and Hispanics for 11.6%. In contrast, the race/ethnic breakdown in the control group was 40% white, 36% African American, 12% Asian, and 10% Hispanic (P<0.0001 for trend).

Results of the health checkup showed that the women who developed gestational diabetes were more likely to have a family history of diabetes (24.6% versus 13.1%, P=0.0011) and had a higher BMI (25.6 versus 23.3, P<0.0001) and a higher serum glucose level (87.7 versus 82.3 mg/dL, P<0.001). Cholesterol and blood pressure values did not differ significantly between the cases and the control group.

In a fully adjusted multivariate model, pregravid mild hyperglycemia was associated with an odds ratio of 4.8 (95% CI 2.1 to 16.5) for gestational diabetes as compared with women who had normal serum glucose levels. Women with a BMI ≥25 had an OR of 2.7 (95% CI 1.6 to 4.3) for gestational diabetes.

Prehypertension/hypertension increased the odds for gestational diabetes by 50%, and hypercholesterolemia did not affect the risk.

The risk of gestational diabetes increased with the number of pregravid cardiometabolic risk factors. Women with three or more risk factors had a 3.6-fold greater risk of gestational diabetes compared with women who had no risk factors (P<0.001).

Hedderson and co-authors performed additional analysis of blood glucose and BMI, the two strongest predictors of gestational diabetes. They found that a serum glucose level ≥87 mg/dL increased the risk of gestational diabetes by 3.1 times compared with women who had lower glucose levels. BMI ≥25 increased the risk by 3.8-fold compared with women who had lower BMI values.

Women with both a serum glucose level ≥87 mg/dL and a BMI ≥25 had a 4.6-fold greater risk of gestational diabetes compared with women who had lower values for both measures (P<0.001).

“Clinicians should be aware that patients with an increasing number of cardiometabolic risk factors … before pregnancy may be at particularly high risk of the development of gestational diabetes and might benefit from early screening or dietary and exercise interventions to prevent the development of gestational diabetes,” the authors wrote in conclusion.

Practice Pearls:
  • Explain that a study of pregravid cardiometabolic risk factors found that the presence of three or more risk factors up to seven years prior to pregnancy increased the risk of gestational diabetes during the pregnancy.
  • Point out that mild hyperglycemia and obesity were associated with the highest risk of gestational diabetes, with odds ratios of 4.8 and 2.7, respectively.

Hedderson MM, et al “Pregravid cardiometabolic risk profile and risk for gestational diabetes mellitus” Am J Obstet Gynecol 2011; DOI:10.1016/j.ajog.2011.03.037