The natural history of somatosensory and autonomic nerve dysfunction in relation to glycaemic control during the first 5 years after diagnosis of type 1 (insulin-dependent) diabetes mellitus.

The natural evolution of neural dysfunction was studied prospectively over 5 years following diagnosis of Type 1 (insulin-dependent) diabetes in 32 patients aged 12-36 years. Motor and sensory nerve conduction velocities, heart rate variation at rest and during deep breathing, and pupillary function were measured at diagnosis and after 3, 12, 24, 48, and 60 months. Thermal and vibration sensation thresholds were determined after 24, 48, and 60 months of diabetes. Mean HbA1 levels of months 3-60 within the normal range of less than 8.3% (7.3 +/- 0.2%) were observed in 13 patients (Group 1), while a mean HbA1 of months 3-60 greater than or equal to 8.3% (10.0 +/- 0.3%) was found in 19 patients (Group 2). Mean nerve conduction was significantly diminished in Group 2 as compared with Group 1 in at least 4 out of 6 nerves tested during months 12-60 (p less than 0.05). Both tests of heart rate variation were significantly impaired in Group 2 as compared with Group 1 after 24 and 60 months (p less than 0.05), but no differences in pupillary function were observed between the groups. Thermal discrimination but not vibration perception thresholds on the foot were significantly higher in Group 2 than in Group 1 at 40 and 60 months (p less than 0.05). Abnormalities in nerve conduction, thermal discrimination, and heart rate variation, but not vibration perception threshold and the pupillary function tests were significantly more frequent in Group 2 than in Group 1 at 60 months (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)