Idiopathic membranous nephropathy in patients with diabetes mellitus: a diagnostic and therapeutic quandary

Background: Proteinuria and renal dysfunction is common in diabetic patients and may occur due to variety of causes. Nondiabetic renal diseases (NDRD) account for 30% of the renal biopsies, and idiopathic membranous nephropathy (iMN) is a common non diabetic glomerular disease that can exist alone or in combination with diabetic nephropathy (DN). Immunosuppressants used in iMN may be associated with complications of worsening glycemic control and recurrent infections. There is a paucity of literature on the clinical course, outcomes and treatment adverse effects of patients with iMN and diabetes. Methods: We retrospectively analyzed the data of all diabetics, evaluated for NDRD and found to have iMN, between January 2000 and June 2015 in our institute. Results: A total of 134 patients with diabetes were biopsied for NDRD and 16 patients had iMN. Mean 6 standard deviation age was 54 +/- 11.77 years and the median duration of diabetes was 9.4 years. Twelve patients had isolated iMN and four patients had iMN coexisting with DN. Response rates of 18%, 35.71% and 63.63% were seen with Modified Ponticelli (MP) regimen, tacrolimus and mycophenolate mofetil (MMF), respectively. Five patients developed treatment-related adverse effects significant enough to necessitate a treatment change. Worsening glycemic control was the most common side effect. Adverse effects were less with the MMF compared with the MP regimen and tacrolimus. Conclusion: Patients with iMN coexisting with diabetes exhibit a poor response to the MP regimen. Treatment-related toxicity is less common with MMF in comparison with the MP regimen and tacrolimus-based regimen. An almost similar response was noted with MMF and tacrolimus-based regimen but there was more withdrawal from treatment due to toxicities observed in the latter.