Background: Diabetes mellitus is a risk factor for early complications and mortality in patients with peripheral artery disease. Lipoprotein (a) [Lp(a)] is also suggested to be a marker of increased cardiovascular risk. We investigated the association and interaction between diabetes mellitus, lipoprotein(a) and mortality in high risk patients with peripheral artery disease (PAD).
Methods: We studied 700 consecutive patients [median age 73 years, interquartile range (IQR) 62-80, 393 male (56%)] with PAD from a registry database. Atherothrombotic risk factors (diabetes, smoking, hyperlipidaemia, arterial hypertension) and Lp(a) serum levels were recorded. We used stratified multivariate Cox proportional hazard analyses to assess the mortality risk at a given patient's age with respect to the presence of diabetes and Lp(a) serum levels (in tertiles).
Results: Patients with Lp(a) levels above 36 mg dL(-1) (highest tertile) and insulin-dependent type II diabetes had a 3.01-fold increased adjusted risk for death (95% confidence interval 1.28-6.64, P = 0.011) compared to patients without diabetes or patients with non-insulin-dependent type II diabetes. In patients with Lp(a) serum levels below 36 mg dL(-1) (lower and middle tertile), diabetes mellitus was not associated with an increased risk for death.
Conclusion: Insulin-dependent type II diabetes mellitus seems to be associated with an increased risk for mortality in PAD patients with Lp(a) serum levels above 36 mg dL(-1). PAD patients with non-insulin-dependent type II diabetes, and patients with diabetes and Lp(a) levels below 36 mg dL(-1) showed survival rates comparable to PAD patients without diabetes.