The characteristics of women in our sample are illustrated in the first section of . Women with diagnosed diabetes were significantly older than women with histories of gestational diabetes or unaffected women and were more likely to report African-American or Non-Hispanic Black race/ethnicity, family history of diabetes, the least favorable poverty to income ratios, the fewest number of alcoholic drinks per day, and the greatest waist circumferences. Unaffected women tended to have the longest leg length and women with histories of gestational diabetes more often tended to be current smokers, but these associations were not significant.
Unadjusted characteristics of unaffected parous women, women with histories of gestational diabetes, and women with diagnosed diabetes. Means (standard errors) or percentages (standard errors) are shown.
In unadjusted comparisons, women with diagnosed diabetes had worsened levels of cardiovascular and metabolic syndrome factors than unaffected women (). In comparison, differences between women with histories of gestational diabetes and unaffected women were less marked. Women with histories of gestational diabetes actually had more favorable cholesterol subtypes and blood pressure levels than unaffected women. The exceptions were fasting insulin and glucose levels. Fasting insulin and glucose did increase across categories of glucose intolerance (). When we examined the number of metabolic syndrome components or cardiovascular risk factors, which dichotomized risk factor levels, the number of components was greatest in women with diagnosed diabetes, followed by women with histories of gestational diabetes. Self-reported cardiovascular was uncommon, reported in 6.7% (n=18) of women with diagnosed diabetes, 0.7% (n=2) of women with histories of gestational diabetes, and 1.6% (n=91) of unaffected women (p=0.048).
When we adjusted for patient covariates, the largest differences were again seen between women with diagnosed diabetes and other groups (). After adjustment for age, race/ethnicity, family history of diabetes, cigarette smoking, and alcohol intake (, Model 1), women with diagnosed diabetes had similar risk factor patterns compared to unadjusted analyses. Women with diagnosed diabetes had poorer LDL, HDL, total cholesterol, systolic blood pressure, insulin, glucose, and microalbumin levels than unaffected women. The exception to this pattern was that uric acid levels, triglyceride levels, and diastolic blood pressure levels no longer differed significantly. Women with diagnosed diabetes were also more likely to have metabolic syndrome and to have ≥3 cardiovascular risk factors than unaffected women. Women with diagnosed diabetes also had poorer HDL and total cholesterol, fasting glucose, and microalbuminuria than women with histories of gestational diabetes.
Predicted probabilities and 95% confidence intervals for cardiovascular and metabolic syndrome risk factors.
After adjustment (, Model 1), women with histories of gestational diabetes still tended to have more favorable risk factor levels compared to unaffected women, although these comparisons were not significant. Women with histories of gestational diabetes had a similar chance of having metabolic syndrome and of having ≥3 cardiovascular risk factors as unaffected women.
After additional adjustment for waist circumference (Model 2), women with diagnosed diabetes no longer differed in their HDL cholesterol levels or systolic blood pressure levels from unaffected women, but the greater presence of microalbuminuria and elevated insulin, glucose, and total cholesterol persisted. Women with diabetes were still more likely than unaffected women to have ≥3 cardiovascular risk factors compared to unaffected women. After additional adjustment for waist circumference (Model 2), women with diagnosed diabetes still had worsened microalbuminuria, insulin, glucose, and total cholesterol compared to women with histories of gestational diabetes. After adjustment for waist circumference, women with histories of gestational diabetes were still more likely to have ≥3 cardiovascular risk factors compared to unaffected women. The addition of waist circumference to demographic risk factors (Model 2) explained a significantly greater proportion of variance than demographic factors alone (Model 1). When waist circumference was not included as an adjuster, as was the case when metabolic syndrome was the outcome, the R2 for multivariable models was much lower than the R2 for the cardiovascular models where the outcome was also dichotomous.
Further adjustment for cardiovascular, leg length, and poverty-index-ratio did not change this pattern for individual cardiovascular risk factors or for the metabolic syndrome and number of cardiovascular risk factors (results not shown). Of note, the additional proportion of variance or the increase in R2 in Models 3, 4, and 5 tended to be slight compared to Models 1 and 2. In other words, models adjusting for demographic factors, behavioral factors, and waist circumference explained similar variance to models that also adjusted for cardiovascular, leg-length, and poverty-index-ratio. This may be because the number of cardiovascular events was low and only small differences in leg-length were observed, and/or the effects of these factors were mediated through others.
In sensitivity analyses, we substituted BMI for waist circumference to determine if this increased the explained variance of the model or otherwise changed point estimates. We found that these BMI models had slightly lower R2 than models with waist circumference and did not have point estimates that differed significantly from models using waist circumference (results not shown). Therefore, we report results with waist circumference. Relatively few women had microalbuminuria levels that were >30 ug/G, so in multivariable models, the urine microalbuminuria/creatinine was dichotomized as <30 ug/G vs. > 30 ug/G and the results expressed in predicted marginal probabilities. We examined whether using the newer cut-off of FPG=100 mg/dl impacted the metabolic syndrome definition; proportions were not significantly different (results not shown). Finally, among women classified as histories of gestational diabetes, 8 (9.4%) had fasting glucose levels > 126 mg/dl and among women classified as unaffected by either histories of gestational diabetes or diagnosed diabetes, 50 (1.2%) had fasting glucose levels > 126 mg/dl. In a sensitivity analysis, we examined only women who had a fasting glucose as well as fasting glucose levels < 126 mg/dl (n=1900), but this did not alter our pattern of effects, so the larger sample is included in this report.