Associations of Serum C-reactive Protein with Fasting Insulin, Glucose, and Glycosylated Hemoglobin : The Third National Health and Nutrition Examination Survey, 1988–1994

Abstract

This study investigated the associations between serum C-reactive protein and fasting blood levels of insulin, glucose, and hemoglobin A1c (HbA1c). Data from the Third National Health and Nutrition Examination Survey (1998–1994) were used. Study subjects included 2,466 men and 2,876 women who were ≥17 years and nondiabetics with an overnight fast for blood draw. C-reactive protein was categorized into low (<0.3 mg/dl), moderate (0.3–0.9 mg/dl), and high (≥1.0 mg/dl) levels. Mean levels of insulin, glucose, and HbA1c were compared across C-reactive protein levels after adjustment for age, ethnicity, education, poverty index, cigarette smoking, alcohol use, and leisure time physical activity. For men with low (n = 1,818), moderate (n = 493), and high (n = 155) C-reactive protein, the adjusted means of insulin were 9.4, 11.7, and 10.5 microunits/ml (p < 0.01); glucose, 99.8, 101.6, and 100.6 mg/dl (p > 0.05); and HbA1c, 5.4%, 5.5%, and 5.5% (p < 0.05). For women with low (n = 1,816), moderate (n = 776), and high (n = 282) C-reactive protein, the adjusted means of insulin were 8.7, 11.2, and 13.7 microunits/ml (p < 0.01); glucose, 95.3, 97.9, and 105.2 mg/dl (p < 0.01); and HbA1c, 5.3%, 5.4%, and 5.6% (p < 0.01). In conclusion, elevated C-reactive protein was associated with higher insulin and HbA1c among men and women and with higher glucose levels among women only. These results suggest a possible role of inflammation in insulin resistance and glucose intolerance.

C-reactive protein, glucose, hemoglobin A, insulin

HbA1c, hemoglobin A1c, MET, ratio of work metabolic rate to resting metabolic rate, NHANES III, Third National Health and Nutrition Examination Survey