Comparison of the Rate of Renal Function Decline in NonProteinuric Patients With and Without Diabetes.

BACKGROUND: Patients with diabetes and chronic kidney disease (CKD) without proteinuria are often believed to have a cause of CKD other than diabetes. It was hypothesized that if this is true, the rate of renal function decline should be similar among nonproteinuric patients with and without diabetes.

METHODS: Patients seen in the nephrology, endocrinology and general internal medicine clinics at the Medical University of South Carolina (MUSC) between 2008 and 2012 with hypertension and diabetes were identified by ICD9 diagnosis codes. Patients with less than 2 measures of serum creatinine, without urine studies over the study period and with proteinuria were excluded. Four hundred seventy-two patients met the inclusion and exclusion criteria and had an initial estimated glomerular filtration rate (eGFR) between 35 and 80 mL/min per 1.73 m2. The annual rate of decline in eGFR was estimated for each patient from the lowest eGFR in each year by fitting a regression model with random intercept and slope.

RESULTS: In unadjusted analyses, the rate of eGFR decline was greater in patients with diabetes than without diabetes (-0.71 versus -0.30 mL · min(-1) · yr(-1), P = 0.03). After adjusting for age, race, sex, baseline eGFR and use of renin-angiotensin-aldosterone system blockade, the rate of decline was still greater among patients with diabetes than among those without diabetes (-0.68 versus -0.36 mL · min(-1) · yr(-1), P = 0.03).

CONCLUSIONS: Patients with diabetes had more rapid decline in kidney function compared with individuals without diabetes, despite the absence of proteinuria. These results suggest that even in the absence of proteinuria, diabetes may be associated with CKD.