Association of Albuminuria Within the Normoalbuminuric Range With All-Cause Mortality in People With Type 2 Diabetes

Aims: To investigate the independent association of albuminuria within the normoalbuminuric range with all-cause mortality in normoalbuminuric people with type 2 diabetes with and without chronic kidney disease (CKD). Materials and Methods: This observational, prospective, multicentre, cohort study enroled 15,773 individuals with type 2 diabetes in 2006–2008. At baseline, albumin excretion rate (AER) and estimated glomerular filtration rate (eGFR) were assessed together with cardiometabolic risk profile, treatments, complications, and comorbidities. All-cause mortality was verified on 31 October 2015. Results: Of the 15,656 participants (99.3%) with valid information on vital status, 11,460 (71.2%) were normoalbuminuric, 9984 (87.1%) without and 1476 (12.9%) with CKD. Normoalbuminuric individuals were stratified into three (< 5, 5–15, and > 15 mg·day−1) or two (< 10 and 10–29 mg·day−1) AER subcategories. When adjusting for age, sex, eGFR, prior cardiovascular disease, cardiovascular risk factors, and treatments, mortality risk was higher in participants with AER 10–29 versus < 10 mg·day−1 (hazard ratio, 1.120 [95% confidence interval, 1.028–1.221], p = 0.009) and 15–29 versus < 5 mg·day−1 (1.243 [1.099–1.406], p < 0.0001). When stratifying by CKD status, the adjusted risk remained significantly increased only for AER 15–29 versus < 5 mg/24 h in individuals with (1.404 [1.111–1.774], p = 0.005) and, to a lesser extent, without (1.167 [1.009–1.350], p = 0.038) CKD. A non-linear association was observed between AER as Log2 transformed continuous variable and mortality. Conclusions: For the same level of kidney function, higher AER within the normoalbuminuric range was independently associated with all-cause mortality, thus supporting to the use of albuminuria-lowering drugs in people with type 2 diabetes and mildly elevated albuminuria.