Epidemiology of diabetic polyneuropathy

The quality of the epidemiologic data on diabetic neuropathies remains poor for a variety of reasons. They include variability in: 1) ascertainment of diabetes mellitus, 2) the clinical varieties of diabetic patients studied, 3) characterization of neurologic dysfunction, 4) abnormal limits for neurologic tests, 5) minimal criteria for neuropathy, 6) correct attribution of non-neurologic disease, 7) correct attribution of type of neuropathy, and 8) assessment of overall severity. It is not possible to adequately characterize and quantitate diabetic polyneuropathies using only one or two clinical or test abnormalities. We are introducing a global score of polyneuropathy which uses transformed numbers for percentile abnormalities of the 7 best tests and combines these with the Neuropathy Impairment Score of lower limbs (NIS[LL]). This NIS(LL)+7 global score appears to provide a much more comprehensive and stable numeric scale by which to diagnose and grade severity of diabetic polyneuropathy than was previously available. It should be useful as a measure of change in diabetic polyneuropathy trials. The staging approach, which we introduced previously continues to provide an important measure of global severity of diabetic polyneuropathy taking into account both symptoms and impairments.