Serum Lipoprotein(a) Concentration in patients with Diabetic Microangiopathy & Neuropathy.

Background: Several epidemiological studies have shown that high plasma concentration of lipoprotein(a) [Lp(a)] is associated with an increased risk for atherosclerotic cardiovascular disease and works as an independent risk factor for atherosclerosis. But, the significance of Lp(a) in diabetic microangiopathy & neuropathy is unclear essentially due to a paucity of relevant studies. This study was designed to evaluate whether Lp(a) concentration may be increased in patients with diabetic microangiopathy & neuropathy. Methods : We studied 96 patients who visited the department of internal medicine in Pusan National University Hospital from May 1995 to May 1996. The patients were grouped according to the presence of diabetic complications(microangiopathy and neuropathy, microangiopathy included retinopathy and nephropathy) and therapeutic modalities(diet, insulin, insulin with oral hypoglycemic agent, and oral hypoglycemic agent). Results: 1) Concentration of Lp(a) was significantly higher(p<0.05) in patients with diabetic retinopathy(nonproliferative, 38.6±33.6 mg/dl, proliferative, 39.5±32.1 mg/dl) than that of patients without retinopathy(23.3±25.3 mg/dl). The duration of diabetes was significantly longer(p<0.05) in patients with diabetic retinopathy(nonproliferative, 12.0 years, proliferative, 13.2 years) than that of patients without retinopathy(5.9 years). 2) Concentration of Lp(a) was significantly higher(p<0.05) in patients with diabetic nephropathy(36.5±39.3 mg/dl) than that of patients without nephropathy(23.3±17.8 mg/dl) and the duration of diabetes was also longer in patients with diabetic nephropathy(10.7±7.2 years vs 6.3±5.8 years, p<0.005). 3) Concentration of Lp(a) was significantly higher and the duration of diabetes was longer in patients with diabetic neuropathy than that of patients without neuropathy(35.9±31.7 mg/dl vs 23.2±25.1 mg/dl, p<0.05 and 10.8 years vs 6.2 years, p<0.005). 4) Concentration of Lp(a) was significantly higher in patients with three complications(53.6 mg/dl, p<0.005) and duration of diabetes was significantly longer in patients with two or three complications(11.3 years, 13.6 years, respectively, p<0.0001). than those in patients without complications. 5) When the patients were subgrouped according to the treatment modalities, there were no significant difference in Lp(a) concentration, however the duration of diabetes was longer in patient group treated with combination of insulin and oral hypoglycemics than that of the other groups(p<0.05). 6) In multivariate logistic regression analysis, concentration of Lp(a) ≥ 50 mg/dl was significantly correlated with diabetic retinopathy & nephropathy, but was not significantly correlated with diabetic neuropathy. Duration of diabetes(≥7 years) and total cholesterol(≥20 mg/dl) were signi5cantly correlated with diabetic retinopathy, nephropathy and neuropathy. Conclusions: Lp(a) concentration is increased in patients with diabetic microangiopathy and neuropathy compared with patients without these complications. So, Lp(a) may works as risk factor for diabetic microangiopathy and neuropathy, and further study to evaluate the role of Lp(a) as a risk factor of such complications would be necessary in large number of patients.