Arteriolar Hyalinosis Predicts Increase in Albuminuria and GFR Decline in Normo- and Microalbuminuric Japanese Patients With Type 2 Diabetes.

OBJECTIVE This study investigated the association between renal histology, as assessed by morphometric analysis using light (LM) and electron (EM) microscopy, and changes in urinary albumin excretion (UAE) and glomerular filtration rate (GFR) in Japanese people with type 2 diabetes in the early stages of diabetic nephropathy. RESEARCH DESIGN AND METHODS We performed percutaneous renal biopsies in 29 patients with type 2 diabetes (22 men, mean +/- SD age 49 +/- 10 years and GFR 119 +/- 27 mL/min/1.73 m(2), with 15 normoalbuminuric [UAE < 20 mu g/min] and 14 microalbuminuric [UAE 20-200 mu g/min]) to clarify which histological factors were associated with changes in UAE and GFR during 8.0 +/- 3.5 years' follow-up. Glomerular structural changes including mesangial volume fraction [Vv(Mes/glom)] were estimated using EM, whereas the index of arteriolar hyalinosis (IAH) score was assessed by LM. Patients underwent annual measurement of GFR using iohexol injection with simultaneous urine collections for UAE. RESULTS Vv(Mes/glom) was negatively correlated with baseline and follow-up GFR but not with UAE. The IAH score was positively correlated with UAE and negatively correlated with GFR at follow-up, but it was not correlated with either UAE or GFR at baseline. GFR at follow-up was significantly decreased from baseline in patients with IAH scores >= 2.0 and significantly lower than in patients with IAH scores < 2.0. Patients with IAH scores < 2.0 showed no significant change in GFR during follow-up. CONCLUSIONS Arteriolar hyalinosis is an additional histological predictor for albuminuria increase and GFR decline in normo- and microalbuminuric Japanese people with type 2 diabetes.