Impaired glucose tolerance (IGT) is a clinical situation characterized by mild hyperglycemia, which is estimated to afflict 7.8% of the Brazilian population. Diabetic neuropathy is the most common complication in diabetes mellitus and it is related to morbidity and lethality in this disease. The association between IGT and peripheral neuropathy is still a matter of great concern. OBJECTIVE In order to determine if IGT is associated with autonomic neuropathy a cross-sectional study in 44 patients with impaired glucose tolerance test (Group 1) was performed. The patients were compared to 43 control individuals (Group 2). Every patient in each group underwent anamnesis and standardized autonomic tests which consisted of heart frequency test, Valsalva maneuver, postural test and sinus arrhythmia. Routine hematologic exams as well as GTT were also made. RESULTS Patients in group 1 had more systemic arterial hypertension, centripetal obesity, fasting and post-feeding hyperglycemia and dyslipidemia when compared with group 2. When we analysed the autonomic tests, the sinus arrhythmia test was abnormal in 54.5% of the patients in group 1 and in 32.5% in group 2 (p = 0.0039) and the Valsalva maneuver was abnormal in 34.1% of group 1 and in 7% of group 2 (p = 0.004). The postural test was not different in both groups (p = 0.334). CONCLUSIONS Our results show that the involvement of the autonomic nervous system was more frequent in patients with IGT when compared to controls. These findings can explain the increased lethality due to vasculopathies observed in this group of patients and also alert physicians to care for patients with impaired glucose tolerance test.