Association between fasting glucose and C-reactive protein in a Japanese population: the Minoh study

To investigate the association between fasting glucose and C-reactive protein (CRP), we examined 1715 Japanese individuals (723 men and 992 women) aged 40-69 years who did not have medication for hypertension, diabetes, or dyslipidemia, a history of cardiovascular disease or CRP levels>10mg/l. There was a statistically significant unadjusted correlation between CRP and each component of the metabolic syndrome, including fasting glucose, fasting insulin, body mass index, systolic blood pressure, diastolic blood pressure, high-density lipoprotein cholesterol (negative), and triglycerides in both men and women. With adjustment for age, cigarette smoking, alcohol intake, and other components of the metabolic syndrome, the CRP increments (as back-transformed) compared with the lowest tertile of normal fasting glucose were 0.99, 1.05, 1.21, and 1.34mg/l (P for trend=0.008) with the second lowest and highest tertiles of normal fasting glucose, impaired fasting glucose, and type-2 diabetes, respectively in men. The respective adjusted CRP increments were 1.12, 1.23, 1.33, and 1.93mg/l (P for trend<0.001) in women. In the stratified analyses of CRP levels by sex, obesity status, and fasting glucose category or the number of components of the metabolic syndrome, an increase in CRP levels was greater in women than men with obesity and higher fasting glucose category (gender interaction: P<0.001) or an increased number of components of the metabolic syndrome (gender interaction: P=0.003). These results indicate that CRP levels increase continuously across the spectrum of fasting glucose in both sexes. This association is more pronounced in women.