C-reactive protein is more strongly related to post-glucose load glucose than to fasting glucose in non-diabetic subjects; the Insulin Resistance Atherosclerosis Study

Aims It has been suggested that cardiovascular disease may be more strongly related to post-challenge glycaemia than to fasting glucose concentrations. We hypothesized that subclinical inflammation, as indicated by elevated serum levels of C-reactive protein (CRP), may partially explain the association of cardiovascular disease with post-challenge glycaemia. Methods We studied the relationship of CRP (measured with a highly sensitive immunoassay) with fasting glucose and 2-h glucose concentrations during an oral glucose tolerance test in non-diabetic subjects from the Insulin Resistance Atherosclerosis Study. Results Spearman correlation analyses and multiple linear regression analyses showed a significant association of both fasting glucose and 2-h glucose concentrations with CRP levels, after adjusting for demographic covariates (age, sex, ethnicity, clinical centre; Spearman correlation coefficients: r=0.18 for fasting glucose, r=0.27 for 2-h glucose, both P<0.0001). However, after additional adjustment for body mass index and waist-hip ratio only 2-h glucose (and not fasting glucose) was significantly related to CRP (r=0.03 for fasting glucose, P=NS; r=0.14 for 2-h glucose, P<0.0001). Adding insulin sensitivity to the multivariate models further weakened the relationship of CRP to 2-h glucose (r=0.07, P<0.05). CRP mean values increased by 2-h glucose category (normal vs. impaired glucose tolerance vs. isolated post-challenge hyperglycaemia). Conclusions Chronic, subclinical inflammation, as indicated by elevated circulating CRP levels, is more strongly associated with post-challenge glycaemia than with fasting glucose levels in non-diabetic subjects. This association is partially independent of body fat and insulin resistance.