Because there are little satisfactory data on change in severity of diabetic polyneuropathy (DP) over time from study of population-based cohorts of diabetic patients in epidemiologic surveys of DP, it is difficult to predict outcome or morbidity or to identify risk factors; it is also difficult to estimate statistical power for use in controlled clinical trials. In this longitudinal study of almost 200 patients from the Rochester Diabetic Neuropathy Study (RDNS) cohort, we assess which symptoms, clinical examinations, tests, or combinations of examinations and tests (composite scores) are best used as minimal criteria for the diagnosis of DP and as a quantitative measure of severity of DP. An abnormality (> or = 97.5th percentile) of a composite score that included the Neuropathy Impairment Score of the lower limbs plus seven tests (NIS(LL)+7 tests), was a better minimal criteria for DP than clinical judgment alone or previously published minimal criteria. First, it provided a more comprehensive assessment of neuropathic impairment. Second, it avoided the overestimated frequency of DP when the minimal criteria for DP was any one or two abnormalities from multiple measurements. Minimal criteria using nerve conduction and reduced heart beat response to deep breathing identified approximately twice as many patients with DP than did clinical examination and vibration detection threshold using CASE IV. This difference could be used to subclassify state 1 DP. Although various individual measures of DP, for example, vibration detection threshold (as evaluated by CASE IV and the 4, 2, and 1 stepping algorithm [see text]), were good measures of worsening, the composite score NIS(LL)+7 tests (assessing neuropathic impairment) was much better at showing monotone worsening. Using this composite score, the average diabetic patient in the RDNS worsened by 0.34 points per year, whereas patients with diabetic polyneuropathy worsened by 0.85 points per year. On the assumption that a therapeutic agent may prevent worsening of DP but not cause improvement, controlled clinical trials of patients with DP would need to be conducted for a period of 3 years to achieve a meaningful change of 2 NIS points (the level of abnormality considered by a Peripheral Nerve Society consensus group to be clinically meaningful).

We found that diabetic microvessel disease, chronic hyperglycemia exposure, and type of diabetes are associated with severity of DPN, and we believe these factors are implicated in its cause. Each of the five markers of microvessel disease was a strong covariate for severity of DPN. Mean GHb predicts severity of DPN better than duration of diabetes, and the latter predicts severity of DPN better than mean fasting plasma glucose. Knowing the severity of microvessel disease, the degree of chronic hyperglycemia exposure, and the type of diabetes provides useful information to evaluate whether a coexisting polyneuropathy and its severity is probably due to diabetes.

Introduction-Test whether physicians can validly and reproducibly diagnose diabetic sensorimotor polyneuropathy (DSPN).Methods-Twelve physicians assessed 24 patients with diabetes mellitus (DM) on consecutive days (576 examinations) with physical features and voice disguised. Results were compared to gold standard 75% group diagnosis and a nerve conduction score (Σ 5 NC nds).Results-Masking of patients was achieved. Reproducibility measured by the kappa coefficient and compared to Σ 5 NC nd varied considerably among physicians: median and ranges: signs 0.8 (0.32 to 1.0); symptoms 0.79 (0.36 to 1.0) and diagnoses 0.47 (0.33 to 0.84) -both low and high scores indicating poor performance. There was substantial agreement between 75% group dx and confirmed NC abnormality. As compared to Σ 5 NC, individual physicians' clinical diagnosis was excessively variable and frequently inaccurate.Discussion-Study physician diagnosis from signs and symptoms were excessively variable, often over-estimating DSPN. Specific approaches to improving proficiency should be tested.

No abstract