The effect of 8 years of strict glycaemic control on peripheral nerve function in IDDM patients: the Oslo study

Abstract

We have investigated the effect of long-term strict glycaemic control on peripheral and autonomic nerve function in 45 IDDM patients (age 18-42 years, diabetes duration 7-23 years) without clinical signs of neuropathy or other neurological disease. They were randomly assigned to treatment either with continuous insulin infusion, multiple injections (4-6 times daily), or conventional treatment (twice daily) for 4 years and followed prospectively for 8 years. Motor and sensory nerve conduction velocities were measured at the start and after 8 years. Autonomic nerve function tests were performed only once, after 8 years. A significant reduction of nerve conduction velocity was observed during 8 years in patients with mean HbA1 more than 10% (n=12, group mean 10.9%, range 10.1-13.2%) compared to patients with HbA1 less than 10% (n=33, group mean 9.0%, range 7.5-9.9%). Change of motor nerve conduction velocity in the peroneal nerve was: -4.8±4.9 (SD) vs -2.2±5.3 m/s (p<0.01). Change of motor nerve conduction velocity in the posterior tibial nerve was: -6.8±5.7 vs -3.9±5.1 m/s (p<0.05). No significant changes were observed in the ulnar nerve. Change of sensoric nerve conduction velocity in the sural nerve was: -8.9±8.0 vs -4.6±5.3 m/s (p<0.05). Multiple regression analysis showed that a change in HbA1 of 1% resulted in a 1.3 m/s change in nerve conduction velocity during 8 years. A significantly lowered heart-rate variation during deep breathing (p<0.05) and heart-rate response to standing (p<0.01) was found in patients with HbA1 more than 10% compared to patients with HbA1 less than 10%. This study confirms that the long-term lowering of blood glucose retards the deterioration in nerve conduction velocity observed in the diabetic nerve. © 1994 Springer-Verlag.