A prospective study of lipoprotein(a) and risk of coronary heart disease among women with type 2 diabetes

Aims: We examined the association between lipoprotein (Lp)( a) and CHD among women with type 2 diabetes. Methods: Of 32,826 women from the Nurses' Health Study who provided blood at baseline, we followed 921 who had a confirmed diagnosis of type 2 diabetes. Results: During 10 years of follow-up (6,835 personyears), we documented 122 incident cases of CHD. After adjustment for age, smoking, BMI, glycosylated HbA1c, triglycerides ( TGs), high- density lipoprotein cholesterol, low- density lipoprotein cholesterol and other cardiovascular risk factors, the relative risk ( RR) comparing extreme quintiles of Lp( a) was 1.95 ( 95% CI 1.07 - 3.56). The association was not appreciably altered after further adjustment for apolipoprotein B-100 or several inflammatory biomarkers. Increasing levels of Lp( a) were associated with lower levels of TGs. The probability of developing CHD over 10 years was higher among diabetic women with substantially higher levels of both Lp( a) (> 1.07 mu mol/1) and TGs (> 2.26 mmol/1) than among diabetic women with lower levels (22 vs 10%, p log- rank test= 0.049). Diabetic women with a higher level of only Lp( a) or TGs had a similar ( 14%) risk. In a multivariate model, diabetic women with higher levels of Lp( a) and TGs had an RR of 2.46 ( 95% CI 1.21 - 5.01) for developing CHD, as compared with those with lower levels of both biomarkers ( p for interaction= 0.413). The RRs for women with a higher level of either Lp( a) (RR= 1.22, 95% CI 0.77 - 1.92) or TGs ( RR= 1.39, 95% CI 0.78 - 2.42) were comparable. Conclusions/ interpretation: Increased levels of Lp( a) were independently associated with risk of CHD among diabetic women.