Morphological diversity of the corneal small fibers in patients with type 1 diabetes mellitus

Introduction: Diabetic neuropathy (DN) affects up to 50% of patients with type 1 diabetes mellitus (T1DM). Clinical manifestations include painful polyneuropathy with autonomic and orthostatic symptoms. Corneal confocal microscopy (CCM) is one of the promising non-invasive methods for DN evaluation and tracking the effectiveness of treatment. Objectives: To perform the early diagnosis of DN in T1DM patients and describe the morphological changes in nerve fibers during the treatment process. Patients and Methods: This prospective study included 77 T1DM patients and 42 healthy controls. All patients underwent CCM and electroneuromyography (ENMG). Twenty-five patients with T1DM and HbA1c 7-10% underwent strict glycemic control with the correction of insulin therapy and the subsequent CCM and ENMG investigations for the second time. Results: In T1DM patients a decrease in the main nerve trunks with age was revealed, as well as an increase in corneal nerve tortuosity (P<0.05). The number of branches of nerve fibers did not change with the increasing age (P=0.07). After reaching T1DM compensation, patients underwent a course of alpha-lipoic acid therapy. Confocal microscopy of the cornea parameters did not undergo significant changes during therapy since significant positive dynamics were noted only in the tortuosity of nerve fibers (P<0.05), which decreased by 11.8%. Conclusion: In patients with T1DM, strict glycemic control, correction of insulin therapy, and courses of alpha-lipoic acid prescription help to reduce the morphological changes of small fiber neuropathy, which can be evaluated by the confocal microscopy of the cornea.