Reversibility of autonomic nerve function in relation to rapid improvement of glycemic control

To determine the reversibility of autonomic nerve function in relation to the rapid improvement of glycemic control, we studied 54 patients with type 2 diabetes mellitus (33 men and 21 women; mean age, 49+/-8 years; mean duration of diabetes, 10+/-7 years). For 4 weeks of admission, the subjects were placed on strict dietary therapy, and 10 of them were under dietary therapy, 16 initially continued treatment with oral hypoglycemic agents, while 28 were treated with insulin. We measured the dark-adapted pupillary area (DAPA) by infrared photography, an indicator of diabetic autonomic neuropathy, on the second and 28th day after hospitalization. The change in FPG (delta FPG = - 111+/-49 mg/dl; mean +/- SD, p<0.001) and the change in HbA1c (delta HbA1c = -1.3+/-0.3%, p<0.001) were significantly improved. We observed significant improvements in the change in DAPA (delta DAPA) of all patients (25.1+/-11.0 vs. 25.7+/-11.6 mm2, delta DAPA = 0.6+/-1.4 mm2, p<0.01) and in those of patients without retinopathy (delta DAPA = 1.0+/-0.6 mm2, p<0.01). No change was observed in those of patients with retinopathy (delta DAPA= -0.02+/-0.3 mm2, NS). The delta DAPA was related to the delta HbA1c (r = -0.479, p<0.001) and also to the diabetic duration (years, r = -0.517, p<0.001). These findings suggest that a rapid improvement of glycemic control improves autonomic nerve function observed in type 2 diabetes with shorter duration. Particular attention should be paid to maintaining strict glycemic control at the stage of diabetic patients without retinopathy and those with shorter duration.