High prevalence and adverse effect of hepatitis C virus infection in type II diabetic-related nephropathy.

Over a 4-yr period in the northeast region of Japan (Tohoku), 3643 patients for whom a renal biopsy was available were screened. In addition, 2370 biopsied patients for whom hepatitis C virus (HCV) serology was available were evaluated. The prevalence of HCV infection was investigated in the 2370 biopsied patients. The highest prevalence of HCV infection was found in type II diabetic-related glomerulosclerosis (II-DGS) (24 of 123; 19.5%). At renal biopsy, clinical and laboratory findings and histologic parameters were comparable between the HCV-positive and -negative II-DGS groups. After renal biopsy, the decline of renal function reflected by the slope of reciprocal serum creatinine (1/S(Cr)) was significantly greater in the HCV-positive group than in the HCV-negative group (P = 0.001). The log-rank test performed on the renal survival curves showed a significant difference in the two groups (P = 0.019). According to a multiple linear regression analysis adjusted for the effect of age, gender, BP, HbA1c, urinary protein excretion, and histologic parameters as covariates, urinary protein excretion (P = 0.011), severe arteriolar hyalinosis (P = 0.006), and HCV infection (P < 0.001) were significantly associated with 1/S(Cr) slope. Finally, HCV infection was randomly examined in 545 outpatients and inpatients with type II diabetes mellitus who did not undergo renal biopsy. Of these, 56 patients were positive for HCV antibody (10.3%), and their proteinuria was heavier than in 489 HCV-negative patients (P = 0.001). This study reveals that HCV infection is present at a high rate in type II diabetic-related nephropathy and may have an adverse effect on the progression of the disease.