Longitudinal assessment of the development of diabetic polyneuropathy and associated risk factors

Aims: To longitudinally assess risk factors for diabetic polyneuropathy (DPN) severity, and to longitudinally assess risk factors for the change of DPN severity during 2-4 years of follow-up. Methods: From 1995 to 1999, 486 Type 2 diabetes patients in general practice were examined annually with regard to DPN severity and its possible risk factors. DPN severity was assessed with a clinical neurological examination (CNE) which included pinprick sense, light touch sense, vibration sense and ankle jerk. Longitudinal (multivariate) linear associations of (change of) CNE score and predicting variables were analysed using multilevel analyses. Results: In this population, 50% of participants were men and had a mean age of 65.4 years, almost one-third (31.7%) of the participants had a CNE score > 4 at baseline and were classified with DPN. CNE score significantly increased during follow-up. Among participants not graded with DPN at baseline, 21.3% progressed towards a CNE score > 4 after 3 years of follow-up. Longitudinal multivariate analyses showed that age, diabetes duration, HbA_1c, height, body mass index and ankle-arm index together best predicted CNE score during follow-up. Change of CNE score during follow-up was best predicted by age, diabetes duration and HbA_1c, with the latter being the strongest predictor. Conclusions: Although several factors are longitudinally associated with DPN, HbA_1c, age and diabetes duration were the best predictors of CNE change during follow-up. Therefore, improving glycaemia remains an important amenable factor in preventing worsening of diabetic polyneuropathy.