Neuropathy and impaired glucose tolerance: an updated review of the evidence.

There has been considerable interest in the possible association between impaired glucose tolerance (IGT) and neuropathy. A systematic literature search (Medline) and review was here performed. Twenty-three studies were evaluated. Fourteen investigated for the presence of neuropathy in patients with IGT. Nine studied patients with chronic idiopathic axonal polyneuropathy (CIAP), for the prevalence of IGT. The findings suggest that a significant proportion of patients with IGT may have neuropathy, particularly of the small-fibre and painful type. Similarly, a significant percentage of patients without another identifiable cause for painful axonal neuropathy may have IGT. This may however not be applicable to all populations. There are issues relating to the reproducibility, reliability and timing of a single glucose tolerance test (GTT) in establishing a diagnosis of IGT. Furthermore, it is possible neuropathic damage may occur at lower glucose levels than those defining IGT. In conclusion, further prospective long-term study of large IGT cohorts with known prestudy IGT duration is required to confirm and answer the many remaining questions about this presumed association. However, at present time, consideration of IGT as potential cause of painful small-fibre neuropathy appears justified, especially as patients may benefit from dietary and physical exercise interventions.