Factors Involved in the Development of Diabetic Kidney Disease in Patients With Slowly Progressive Type 1 Diabetes Mellitus: A Retrospective Cohort Study

Introduction The duration of diabetes mellitus (DM), blood pro-inflammatory markers, and dipeptidyl peptidase 4 (DPP4) activity are known predictors of diabetic kidney disease (DKD) progression in acute-onset type 1 DM (AT1DM) and type 2 DM. However, predictors of DKD progression in slowly progressive type 1 insulin-dependent DM (SPIDDM) have been less frequently studied. Patients and methods This retrospective cohort study included 60 patients with SPIDDM (definite) (26 men/34 women). We utilized Cox proportional hazard analyses to determine whether characteristics and laboratory findings at the time of the SPIDDM diagnosis were associated with subsequent DKD progression. The urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) at the last outpatient clinic visit served as indicators of renal function. Also, to compare blood markers in patients with SPIDDM, we included 21 patients diagnosed with AT1DM at the same department during the same period and 50 healthy adult volunteers. Results In patients with SPIDDM (definite), the multivariate Cox proportional hazard analysis revealed that the body mass index (BMI), high-sensitivity C-reactive protein (hs-CRP) levels at diagnosis, and the duration of DM prior to SPIDDM diagnosis were associated with the new onset of albuminuria and systolic blood pressure (SBP) at diagnosis, and the duration of DM prior to SPIDDM diagnosis was associated with a decline in eGFR to less than 60 ml/min/1.73 m². Additionally, serum hs-CRP levels were significantly higher in the SPIDDM (definite) group compared to both the AT1DM patients and healthy controls, suggesting a higher inflammatory state in patients with SPIDDM at the time of diagnosis. In patients with SPIDDM (definite) who were not treated with a DPP4 inhibitor, plasma DPP4 activity was associated with the new onset of albuminuria. Conclusions BMI, SBP, hs-CRP levels, DPP4 activity at SPIDDM diagnosis, and the duration of DM prior to SPIDDM diagnosis are associated with subsequent progression of DKD in SPIDDM. Also, we found that the patients with SPIDDM are often already being treated as DM for a long period of time at the time of diagnosis, which may be linked to their already high inflammatory status at the time of SPIDDM diagnosis and contribute to DKD progression. These findings underscore the importance of early diagnosis and management in preventing DKD progression in this population.