Gestational diabetes mellitus is associated with increased C-reactive protein concentrations in the third but not second trimester

Objectives Serum C-reactive protein (CRP) concentrations were measured longitudinally throughout pregnancy to test the hypothesis that CRP could relate more closely to glucose tolerance than to adiposity. Methods The CRP concentrations in pregnant women with normal glucose tolerance (NGT) and those with gestational diabetes mellitus (GDM) were measured at the same time as the oral glucose tolerance test (OGTT), at the 24(th) and 28(th) weeks of gestation and between the 37(th) and 38(th) weeks of gestation. Results At the end of the third trimester, women with GDM had significantly higher CRP levels than women with NGT [median (interquartile range), 9.7 mg L-1 (5.4-16.0) and 5.7 mg L-1 (5.1-7.2); P < 0.001, respectively], but at the time of the diagnostic OGTT no significant difference between the two groups was observed. This was owing to a significant increase of CRP in women with GDM between the time of the OGTT and the 37(th)-38(th) gestational weeks [median (interquartile range), 1.9 mg L-1 (-2.2, 6.7); P = 0.01]; whereas, no change in CRP was found in women with NGT [median (interquartile range), -0.1 mg L-1 (-2.4, 3.1); P = 0.76]. Multiple linear regression analysis showed only a significant independent influence of GDM (P < 0.001) on maternal CRP concentrations in the 37(th)-38(th) gestational weeks and a significant influence of body mass index (P < 0.007), but no influence of GDM at the time of the OGTT. Conclusion These data suggest that in women with gestational diabetes the CRP concentration is primarily related to the degree of adiposity until the second trimester and that thereafter impaired glucose metabolism appears to be the predominant predictor of changes in CRP.