Objectives: To report and characterize two forms of disabling progressive peripheral neuropathy in patients with diabetes mellitus, which respond to anti-inflammatory and/or anti-immune treatment.
Design: Review of clinical, electrophysiologic, and pathologic findings and results of treatment.
Setting: University medical center.
Patients: Twenty-one patients with diabetes mellitus to whom we gave anti-inflammatory and/or anti-immune treatment for progressive peripheral neuropathy during the past 6 years.
Main outcome measures: Patients were interviewed and examined at intervals before and after beginning treatment with intravenous immunoglobulin (n = 15), prednisone (n = 13), cyclophosphamide (n = 5), plasma exchange (n = 3), and azathioprine (n = 1) (alone or in combination).
Results: Fifteen patients had evidence of axonal neuropathy by electrophysiologic studies (group A). All 15 patients had non-insulin-dependent diabetes mellitus, 10 patients had weight loss, and 13 patients had prominent involvement of thighs and/or thoracic bands consistent with diabetic amyotrophy or mononeuropathy multiplex. Small vessel disease was seen in all 10 patients who underwent biopsy, with perivascular or vascular inflammation seen in seven patients. Six patients had demyelinating neuropathy by electrophysiologic criteria (group B). All these patients had insulin-dependent diabetes mellitus, and no one had weight loss. The process was asymmetric in three patients and involved thoracic or abdominal regions in two patients. Onion bulbs were seen in all four patients who underwent biopsy, but no vascular inflammation or occlusion was seen. In all patients in both groups, worsening of their conditions stopped and improvement started after beginning treatment.
Conclusion: Neuropathies responsive to anti-inflammatory and/or anti-immune therapy in patients with diabetes mellitus include (1) multifocal axonal neuropathy caused by inflammatory vasculopathy, predominantly in patients with non-insulin-dependent diabetes mellitus, indistinguishable from diabetic proximal neuropathy or mononeuropathy multiplex, and (2) demyelinating neuropathy indistinguishable from chronic inflammatory demyelinating polyneuropathy, predominantly in patients with insulin-dependent diabetes mellitus.