Evaluation of a simple, random urine test for prospective analysis of proteinuria in Type 2 diabetes: a six year follow-up study

Abstract

Aim: To assess the usefulness of an estimated proteinuria (EPE) using the protein to creatinine ratio (P/C ratio) in a random urine sample for follow-up evaluation of kidney function in diabetic patients. Research designs and methods: 410 newly registered Type 2 diabetic patients had annual follow-up for 6 years (M:F 263:147). EPE was calculated by estimation of P/C ratio in random urine sample. Based on the EPE they were divided into those with normal protein excretion (<100 mg/dl), mild proteinuria (100 to <500 mg/dl) and nephropathy (persistent proteinuria >500mg/dl) cases. The study subjects were divided into 4 groups based on the proteinuria status at follow-up. Anthropometry, measurement of blood pressure and retinopathy were carried out for all study subjects. Results: at the baseline, 342 (83.4%) had normal protein excretion, 53 (12.9%) had mild proteinuria and 15 (3.7%) had nephropathy. At the follow-up the respective numbers were 276 (67.3%), 64 (15.6%) and 70(17%). During the study period nephropathy developed in 55 (13.4%) and mild proteinuria in 11 (2.7%). Nephropathy developed in 32 (6.7%) subjects in the non-proteinuria group and in 23 (43.4%) of the mild proteinuric subjects. Conversion to nephropathy was greater in the latter group ( χ 2=41.6, P<0.0001). Nephropathy cases had higher duration of diabetes at the baseline (8.8±6.4 years) and at follow-up (7.1±6.0 years) and higher prevalence of hypertension when compared with non-proteinuric group (60 and 43.5% compared with 11.1%, P<0.01). New cases of hypertension were detected in 32.8% of proteinuric and 0.7% of normal protein excretion subjects ( χ 2=32.24, P=0.0001). During the follow-up 55 of the 70 nephropathy subjects (78.6%) developed retinopathy compared with ten out of the 276 subjects with normal protein excretion (3.6%) ( χ 2=200.6, P=0.0001). Conclusion: EPE is useful in serial evaluation of kidney function. The risk conferred by hypertension, mild proteinuria and duration of diabetes in producing nephropathy are also highlighted. EPE could be used in developing countries to assess the renal function on a follow-up basis.