Medical records of > or = 40 years old female seen at University Hospital from June/93 to July/95 were submitted to a cross-sectional study. According to Chagas' disease tests, patients were divided into chagasic (n = 362) and controls (n = 285). Diabetes mellitus was defined on the basis of two fasting blood glucose levels > or = 140 mg/dl and hyperglycemia as fasting blood glucose > 110 mg/dl. Chagasic patients were divided into groups with the cardiac form of the disease (n = 179), with megas (n = 58), and asymptomatic (n = 125). Groups were compared by the chi 2 test, analysis of variance, Student's "t" test, and Kruskal-Wallis and Mann-Whitney tests. A significant difference was assumed when p < 0.05. Chagasic and control groups were matched for age, white color and body mass index. Diabetes mellitus was more prevalent in patients with the cardiac form of Chagas' disease than in controls, or patients with the megas or the asymptomatic form (15.1%, 7.4%, 7.4%, and 5.6%, respectively); the same was observed for hyperglycemia (37.4%, 26.7%, 25.9%, 27.2%), in agreement with the hypothesis that the reduced parasympathetic activity caused by Trypanosoma cruzi leads to relative sympathetic hyperactivity.