Patients with Type 2 (non-insulin-dependent) diabetes mellitus complicated by microalbuminuria or albuminuria, have an increased risk of developing macrovascular disease and of early mortality. Because lipoprotein abnormalities have been associated with diabetic nephropathy, this study tested the hypothesis that levels of apolipoprotein (a) are elevated in patients with Type 2 diabetes and increased levels of urinary albumin loss. Levels of apolipoprotein (a) in diabetic patients with microalbuminuria (n = 26, geometric mean 195 U/l, 95% confidence interval 117-324) and albuminuria (n = 19, 281 U/l, 165-479) were higher than in non-diabetic control subjects (n = 140, 107 U/l, 85-134, p < 0.05), and in the albuminuric group than diabetic patients without urinary albumin loss (n = 58, 114 U/l, 76-169, p < 0.05). Patients with microalbuminuria and albuminuria had levels comparable with patients undergoing elective coronary artery graft surgery (n = 40, 193 U/l, 126-298). Apolipoprotein (a) levels were higher in diabetic patients with macrovascular disease than in those without (n = 49, 209 U/l, 143-306 vs n = 54, 116 U/l, 78-173, p < 0.05). These preliminary results suggest that raised apolipoprotein (a) levels of Type 2 diabetic patients with microalbuminuria and albuminuria may contribute to their propensity to macrovascular disease and early mortality.

Patients with insulin-dependent diabetes mellitus (IDDM) have a significantly increased risk of macrovascular disease, particularly if they have persistent proteinuria. To determine whether altered levels of apolipoprotein(a) [apo(a)], the plasminogenlike glycoprotein of the potentially atherogenic lipoprotein(a); contribute to the increased risk of atherosclerosis, apo(a) levels were measured in 107 patients with IDDM and compared with nondiabetic control subjects and male elective coronary artery graft patients. Apo(a) levels were increased in diabetic patients with microalbuminuria (geometric mean 245 U/L, 95% confidence interval [CI] 142-427, n = 30) and albuminuria (mean 196 U/L, 95% CI 97-397, n = 18) with levels comparable to patients with coronary artery disease (mean 193 U/L, 95% CI 126-298, n = 40), which were higher than in the control group (mean 107 U/L, 95% CI 85-134, n = 140; P = 0.016). Apo(a) levels in diabetic patients without microalbuminuria (mean 86 U/L, 95% CI 63-116, n = 59) were comparable with the control population and less than in those with microalbuminuria (P less than 0.001) and albuminuria (P = 0.014). The elevated apo(a) levels found in patients with IDDM and increased urinary albumin loss may contribute to their heightened risk of macrovascular disease.

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