Prevalence and Risk Factors of Microalbuminuria in a Cohort of African-American Women With Gestational Diabetes

Abstract

OBJECTIVE—To study the prevalence of microalbuminuria (MA) in African-American women with a history of gestational diabetes (GDM) who are at high risk for insulin resistance and renal dysfunction and to study MA’s relation to insulin resistance, type 2 diabetes, and hypertension.

RESEARCH DESIGN AND METHODS—MA was assessed using 24-h, timed, and/or random urine samples in a cross-sectional sample (n = 289) from a cohort of African-American women with a history of GDM and followed for a median of 11 years (range 3.0–18.4) since their diabetic pregnancy. Subjects with a urine albumin excretion rate of 30–300 g/24 h or 30–300 μg/mg creatinine in a random sample were classified as having MA if two of three samples over a 3- to 6-month period were positive. These women were evaluated for family history of diabetes, smoking and alcohol use, BMI, diabetes, hypertension, and lipid abnormalities. Insulin sensitivity was determined using the homeostasis model assessment (HOMA) estimates, which used fasting insulin and glucose measurements obtained at the same time as the MA urine sample.

RESULTS—At MA assessment, the women ranged in age from 22 to 57 years, with a median of 39 years. The overall prevalence of MA was 20%; 36% in those with diabetes. Those women with MA had higher rates of diabetes (63.8 vs. 28.6%, odds ratio [OR] = 4.4, P < 0.05), hypertension (82.8 vs. 42.9%, OR = 6.4, P < 0.05), and family history of diabetes (85.7 vs. 61.7%, OR = 3.7, P < 0.05). The proportion of subjects with MA with a family history of hypertension was nonsignificantly increased (92.9 vs. 82.4%). Subjects with MA were more obese (BMI 37.2 ± 8.9 vs. 34.4 ± 8.6 kg/m²) and had higher levels of HbA_1c (8.8 ± 3.3 vs. 6.6 ± 1.8%, P < 0.001) and systolic (144.3 ± 25.9 vs. 122.8 ± 17.2 mmHg, P < 0.0001) and diastolic (95.1 ± 15.4 vs. 82.5 ± 11.9 mmHg, P < 0.0001) blood pressures. Lipid fractions were similar in those with and without MA. Although fasting glucose was much higher in subjects with MA (10.3 ± 5.8 vs. 7.1 ± 4.2 mmol/l, P = 0.0002), insulin levels were not significantly higher in subjects with MA (17.4 ± 21.2 vs. 15.2 ± 12.4 pmol/l). Insulin sensitivity, as measured using log HOMA, was similar (1.5 ± 0.6 vs. 1.6 ± 0.6) in women with and without MA, respectively. Multivariable logistic regression analyses indicated that HbA_1c, OR = 1.16 (1.07, 1.27), and systolic blood pressure, OR = 1.27 (1.14, 1.41), were independent risk factors for MA. In those with diabetes, the subjects with MA had higher rates of hypertension—83.8 vs. 56.1%, OR = 4.1 (1.5, 11.10)—which was reflected by their higher systolic and diastolic blood pressures, 146.1 mmHg (P = 0.001) and 94.8 mmHg (P = 0.002), respectively, and lower levels of VLDL (0.45 ± 0.22 vs. 0.61 ± 0.33 mmol/l, P = 0.021). In the multivariable analyses of those with diabetes, the two independent risk factors for MA were similar: HbA_1c, OR = 1.13 (1.01, 1.28), and systolic blood pressure, OR = 1.21 (1.04, 1.41).

CONCLUSIONS—African-American women with a history of GDM have one of the highest rates for MA. Presence of MA was not associated with insulin resistance but was significantly independently associated with HbA_1c levels and hypertension. These results, taken in context of the literature, suggest that hypertension and glucose intolerance, in part, influence MA through different mechanisms. Because of the high prevalence of MA in this population and MA’s relation to all-cause and cardiovascular mortality, screening for MA should be considered.