Urinary protein excretion in Type 2 diabetes with complications

This study examined the association between urinary markers of early diabetic nephropathy and non-renal diabetic complications in 946 patients with type 2 diabetes mellitus. The association with hypertension was also studied. Data on macrovascular complications (ischaemic heart disease, stroke, peripheral vascular disease) and microvascular complications (retinopathy, peripheral neuropathy) were obtained from case records and clinical examination. Urine samples collected were analysed for albumin, beta(2)-microglobulin, retinol-binding protein (RBP), and N-acetyl-beta-D-glucosaminidase (NAG). Results showed that urinary albumin, RBP and beta(2)-microglobulin levels were higher in patients with macro- and/or microvascular complications, compared to those without. NAG levels were higher only in patients with both types of complications. A higher proportion of patients with complications had abnormally raised urinary protein and enzyme levels, compared to those without. Patients with associated hypertension had higher urinary levels of albumin and beta(2)-microglobulin, regardless of whether complications were present or not. RBP excretion was, however, markedly higher only in patients with microvascular complications, whereas hypertension did not influence NAG excretion. Urine albumin and RBP excretion were predictive of microvascular, as well as both macrovascular and microvascular complications, whereas NAG excretion was predictive of macro- and microvascular complications. These findings could mean that increased urinary protein and enzyme excretion were associated with more severe disease in these patients.