High prevalence of neuropathy in patients with impaired 60-minute oral glucose tolerance test but normal fasting and 120-minute glucose levels.

AIM: The aim of this study was to define the prevalence of neuropathy in patients with impaired 60-min oral glucose tolerance test (OGTT) but normal fasting and 120-min glucose levels and to evaluate risk factors for polyneuropathy and glucose intolerance. METHODS: The hospital files of 320 patients (56.5+/-11.9 years, 73.1% female), who had both electrodiagnostic test for sensory symptoms (nerve conduction studies and needle electromyography) and OGTT in maximum 6 months apart, were studied in this retrospective design study. Serum glucose levels at fasting and 0-, 30-, 60-, 90- and 120-min of OGTT and some biochemical parameters were recorded. RESULTS: Fifteen percent of patients had diabetes mellitus (DM) and 10.9% and 5.6% had impaired fasting glucose (IFG) and impaired glucose tolerance (IGT). Twenty-one patients (6.6%) had only impaired 60-min blood glucose levels. Polyneuropathy was found in 44.4%, 28.5%, and 50.0% of patients with IGT, IFG and DM respectively. The prevalence of polyneuropathy was significantly higher in patients with impaired 60-min than OGTT normal subjects (52.4% vs 21.7% p=0.003). Fasting blood glucose, HDL, LDL and TSH levels, age, glucose intolerance low serum folic acid and significantly increased polyneuropathy risk. Age, weight, body mass index, high fasting, 30, 60-, 90-, 120-min serum glucose, insulin and HgA1c levels were risk factors for glucose intolerance. CONCLUSION: Since the prevalence of neuropathy in patients with impaired 60-min glucose levels is high, it would be valuable to look at 60-min glucose levels to detect abnormal glucose metabolism and the neuropathy earlier in the course.