Ten patients with biopsy-confirmed IgA nephropathy associated with diabetes mellitus underwent dietary weight control and three courses of intravenous pulses of methylprenisolone followed by prednisolone for 6–12 months and tonsillectomy. The average length of the follow-up period was 47.8 (range 30–96) months. As compared with pretreatment values, hematuria, proteinuria, body mass index, and hemoglobin A<sub>1c</sub> were significantly improved after treatment. There were no significant differences with regard to blood pressure and glycemic blood glucose control. There was no worsening of diabetic retinopathy and nephropathy. During steroid pulse therapy, the patients who were treated with insulin needed a higher dosage of insulin; after steroid pulse therapy, the dosage returned to baseline. Even patients with IgA nephropathy and diabetes mellitus could be treated with combined therapy and showed beneficial responses, it they succeeded in reducing body mass index.