Undiagnosed chronic kidney disease in people with type 2 diabetes in Spain: Prevalence, treatment patterns and associated factors in a multicentre cross-sectional study.

Abstract

BACKGROUND AND AIM: Chronic kidney disease (CKD) remains underdiagnosed in people with type 2 diabetes mellitus (T2DM), particularly in early stages, despite its strong association with renal disease progression, cardiovascular outcomes, and current guideline recommendations for early cardio-renal protective interventions. Contemporary, nationally representative primary care data from Spain evaluating CKD underdiagnosis in people with T2DM are limited. This study estimated the prevalence of diagnosed and undiagnosed CKD in adults with T2DM in Spain, described treatment patterns by CKD diagnosis status, and identified factors associated with undiagnosed CKD. METHODS: A planned secondary analysis of the DIAMOND2 multicentre cross-sectional study was performed in Spanish primary care. Data were retrospectively collected from electronic medical records during the calendar year 2022, and the analysis was performed between January and July 2023. Data from 5009 adults with T2DM randomly selected from 70 centres were analysed. CKD was defined according to KDIGO 2024 criteria as estimated glomerular filtration rate (eGFR) <?60?mL/min/1.73?m² and/or urine albumin-to-creatinine ratio (uACR) ??30?mg/g. Patients were classified as having diagnosed CKD (recorded), undiagnosed CKD (meeting criteria without record), or no CKD. Descriptive statistics were used, and multivariable Poisson regression models with robust variance were fitted to identify factors associated with undiagnosed CKD. RESULTS: True CKD prevalence was 32.0?%, with 54?% undiagnosed. Undiagnosed CKD was mainly in patients with isolated eGFR or uACR abnormalities and lower KDIGO risk. SGLT2 inhibitors were prescribed to 45.2?% of diagnosed and 40.0?% of undiagnosed CKD, versus 35.4?% without CKD (p?<?0.001). In multivariable analysis, undiagnosed CKD was associated with metformin use and higher eGFR, and inversely with diabetes duration, heart failure, and proliferative retinopathy. CONCLUSIONS: Over half of CKD cases in Spanish adults with T2DM remain undiagnosed, particularly at early disease stages, limiting risk stratification and optimal cardio-renal management. These findings underscore the need for systematic CKD screening and improved recognition of early kidney disease in primary care.