Young‐onset type 2 diabetes mellitus enhances proteinuria, but not glomerular filtration rate decline: A Japanese cohort study

Aims/Introduction The time course of chronic kidney disease in young‐onset type 2 diabetes mellitus remains unclear. We compared the trajectories of proteinuria and estimated glomerular filtration rate (eGFR) decline between young‐onset (aged ≤40 years) and late‐onset (aged >40 years) type 2 diabetes mellitus in a Japanese multicenter cohort. Materials and Methods Participants without diabetic kidney disease were divided into two groups according to age at diagnosis: young‐ and late‐onset. The primary endpoint was eGFR <60 mL/min/1.73 m 2 , proteinuria or both. Multivariable Cox proportional hazards were calculated to estimate incidence. Results Among 626 participants with type 2 diabetes mellitus, 78 (12.4%) had young‐onset and 548 (87.6%) had late‐onset diabetes. The incidence of eGFR <60 mL/min/1.73 m 2 was lower (16.7% vs 33.5%, P = 0.003), but that of proteinuria was higher (46.2% vs 28.9%, P = 0.002) in the young‐onset type 2 diabetes mellitus group. The Kaplan–Meyer curve showed that young‐onset type 2 diabetes mellitus was associated with a decreased hazard ratio (HR) for eGFR <60 mL/min/1.73 m 2 and an increased HR for proteinuria compared with late‐onset type 2 diabetes mellitus. In the multivariate Cox analysis, young‐onset type 2 diabetes mellitus increased the HR (95% confidence interval) of proteinuria (1.53, 95% confidence interval 1.03–2.26), but did not change the eGFR <60 mL/min/1.73 m 2 HR. Conclusions Young‐onset type 2 diabetes mellitus has a lower HR of eGFR <60 mL/min/1.73 m 2 and an increased HR of proteinuria compared with late‐onset type 2 diabetes mellitus, indicating that young‐onset type 2 diabetes mellitus has a different time course for the development of proteinuria and subsequent eGFR decline.