Differences in glycemic control and survival predict higher ESRD rates in diabetic first nations adults

Abstract

Diabetic First Nations people (FN) have higher ESRD rates than other Canadians but the reasons remain unclear. We sought to better understand this disparity by comparing demographic, laboratory and survival features of diabetic FN and other Saskatchewan residents (OSK) by renal function stage. Prevalent diabetes cases in 2005/06 were identified in Saskatchewan's two largest health regions using administrative databases, and linked with centralized laboratory tests. They were sub-divided into five stages of renal function using estimated glomerular filtration rates (eGFR) that were determined in 992 of 2,321 FN (42.7%) and 14,054 of 21,886 OSK (64.2%). Age, sex, urine microalbumin (MA), glycosylated hemoglobin (A1C), low density lipoprotein cholesterol (LDL-C) and two year mortality risk was compared for all subjects. Diabetic FN were younger (mean age 52.7 vs. 64.2, p < 0.0001), more likely to be female (59.6% vs.45.4%, p < 0.001), had increased MA (56.6% vs. 48.4%, p < 0.0001) and displayed higher mean A1C levels (8.16% vs.7.36%, p < 0.0001) than OSK. Despite a larger proportion having eGFR's > 60 ml/min (87.0% vs.77.3%, p < 0.001), FN were also more likely to have ESRD (2.3% vs.0.8%, p < 0.001). Although FN with eGFR's > 30 ml/min experienced higher age/sex adjusted mortality risk than OSK, the trends for both adjusted and unadjusted mortality risks for those with advanced pre-ESRD renal failure were lower for FN than for OSK. Elevated rates of ESRD experienced by FN with diabetes are related to poorer glycemic control at all levels of renal function, and lower age-related mortality at advanced stages of chronic kidney disease.