Elevated C-reactive Protein Levels Independently Predict the Development of Prediabetes Markers in Subjects with Normal Glucose Regulation.

AIMS: Prediabetes is a precursor of diabetes and increases the risk of cardiovascular disease. Individuals with prediabetes reportedly have higher C-reactive protein levels, which is a risk factor for diabetes, relative to individuals with normal glucose regulation. Inflammation may play a role in the very early-phase deterioration of glucose metabolism, although there is insufficient knowledge regarding this relationship. Thus, we examined the association between serum C-reactive protein level and the development of three prediabetes markers.

METHODS: This study included 743 subjects with normal glucose regulation at baseline who completed oral glucose tolerance tests at baseline and after approximately 5 years. Subjects with a history of cardiovascular disease were excluded.

RESULTS: During the 5-year follow-up, 55 subjects developed isolated impaired glucose tolerance (IGT; 2h-plasma glucose levels of 7.8-11.0 mmol/L), 24 subjects developed isolated impaired fasting glucose (IFG; fasting plasma glucose levels of 6.1-7.0 mmol/L), 3 subjects developed IFG plus IGT, and 53 subjects developed isolated elevated glycated hemoglobin levels (HbA1c; level of 41-47 mmol/mol). The multivariate analysis revealed that, relative to the lowest quartile, the highest serum C-reactive protein quartile was independently associated with an increased risk of developing isolated elevated HbA1c levels (odds ratio: 2.95, 95% confidence interval: 1.16-7.51, P =0.024) and marginally associated with an increased risk of developing impaired glucose tolerance plus diabetes. However, C-reactive protein levels were not associated with an increased risk of developing IFG.

CONCLUSIONS: Elevated serum C-reactive protein levels independently predicted elevated HbA1c levels, but not IFG.