Relationship Between Serum Total Bilirubin Concentration And Macrovascular Complications In Patients With Type 2 Diabetes Mellitus

Objective: The presence of more than one atherosclerotic macrovascular disease (cerebrovascular, cardiovascular, and peripheral arterial diseases) in the same patient is called polyvascular disease, which carries a very high cerebro- and cardiovascular morbidity and mortality. Recently, hypobilirubinemia is recognized as a possible risk factor for the development of atherosclerosis besides classical risk factors such as hypertension, hyperglycemia, and hyperlipidemia. We investigated this study to clarify the pathophysiological significance of total bilirubin in type 2 diabetic patients complicated by polyvascular diseases. Design and method: This is a retrospective cross-sectional study including 696 type 2 diabetic patients. First, we compared serum total bilirubin concentration (TBC) between patients with and without cerebrovascular disease (CBVD), coronary artery disease (CAD), and peripheral arterial disease (PAD). Secondly, we performed logistic regression analyses in order to find independent risk factors for atherosclerotic cerebro- and cardiovascular diseases (CBVD, CAD, and PAD). Lastly, we compared TBC among the patients with none, one, and two or three macrovascular diseases. Results: Among 696 type 2 diabetic patients, 106, 131, and 45 patients were complicated by CBVD, CAD, and PAD, respectively. Patients with CBVD and PAD showed significantly lower serum TBC than those withoutCBVD and PAD (CBVD: 0.67 ± 0.25 vs. 0.76 ± 0.38 mg/dL, p = 0.011, PAD: 0.65 ± 0.26 vs. 0.76 ± 0.34 mg/dL, p = 0.030). In addition, there was a tendency that TBC was lower in patients with CAD than in those without CAD (0.69 ± 0.27 vs. 0.76 ± 0.33 mg/dL, p = 0.06). It was shown that TBC was an independent risk factor for CBVD (p = 0.022), but not for CAD (p = 0.35) or PAD (p = 0.19). TBC of the patients with none (n = 469), one (n = 172), two (n = 51) or three (n = 4) macrovascular diseases were 0.77 ± 0.39, 0.65 ± 0.27, and 0.60 ± 0.37 mg/dL, respectively. Conclusions: Diabetic patients without macrovascular diseases exhibited the highest TBC among three categories of the patients. On the other hand, patients with two or three macrovascular complications showed the lowest TBC. Therefore, TBC can be used as a possible biomarker which identifies type 2 diabetic patients with polyvascular disease.