Microalbuminuria is thought to be a risk factor for progression to macroalbuminuria, an indicator of renal functional decline in patients with type 1 or 2 diabetes. However, it remains unknown which renal histological factors predict the onset of macroalbuminuria or eGFR<60 mL/min/1.73 m2 (chronic kidney disease, CKD) during early diabetic nephropathy. Therefore, we sought to determine which histological factors, including index of arteriolar hyalinosis (IAH), are predictors for onset of macroalbuminuria and CKD. The study population consisted of 35 patients with type 2 diabetes (25 men; age, 47±9 years; eGFR, 92.7±18.0 mL/min/1.73 m2) with normoalbuminuria or microalbuminuria who underwent percutaneous renal biopsy. We followed these patients for at least 5 (18±6) years. The study endpoint was the onset of macroalbuminuria or CKD, or by March 2020. Light and electron microscopy-based morphometric analyses were performed to quantitatively evaluate glomerular and interstitial structural changes. During the observation period, 9 of 35 patients progressed to macroalbuminuria and 15 had CKD. The annual rate of eGFR decline was significantly related to IAH (r=-0.40, p=0.016), but not any other histological parameters. Kaplan-Meier analysis revealed that arteriolar hyalinosis and mesangial expansion are associated with a significantly higher risk of onset of macroalbuminuria and CKD, and microalbuminuria grade is associated with the onset of macroalbuminuria, but not the onset of CKD.
Conclusions: Aggravated arteriolar hyalinosis is a histological risk factor for renal functional decline and predicts the onset of macroalbuminuria and CKD in patients with type 2 diabetes, normo-microalbuminuria, and normal renal function regardless of microalbuminuria grade. This finding might reflect initial changes in early diabetic nephropathy.
T. Moriya: None. A. Hayashi: None. A. Suzuki: None. M. Matsubara: None. M. Ouchi: None.
