BACKGROUND The aim of this study was to investigate the blood pressure (BP) response to exercise in normotensive patients with type II diabetes mellitus (DM). METHODS A cross-sectional study was carried out on 75 normotensive subjects with type 2 DM (group 1), and 70 age-gender matched normotensive healthy volunteers (group 2). Treadmill exercise test, 24-h ambulatory BP monitoring (ABPM) were performed for each patients and healthy volunteers. RESULTS There were 67 patients (mean age 52 ± 9 years and 42% male) in group 1 and 68 healthy volunteers (mean age 51 ± 7 years and 43% male) in group 2. Eight patients from group 1 and 2 subjects from group 2 were excluded because of high BP on ABPM. Groups were similar for systolic BP (SBP) and diastolic BP (DBP) on office measurements and on ABPM. Groups were similar for rest SBP, DBP, heart rate, exercise duration on exercise test. Peak SBP was significantly higher in group 1 than in group 2, but peak DBP was not (196.9 ± 18 vs 165.9 ± 18.6 mmHg, p<0.001; 88.1 ± 11.6 vs 86.2 ± 8.7 mmHg, p = 0.283, respectively). Hypertensive response to exercise (HRE) was more frequent in group 1 than in group 2 [39 (58%) vs 6 (9%), p<0.001]. Independent predictors of peak SBP were DM, office SBP and male gender, while independent predictors of HRE were DM, office SBP and age in multivariate analysis. CONCLUSIONS SBP response to exercise is exaggerated in normotensive diabetic patients compared with non-diabetic subjects. DM, office SBP and male gender are independent predictors of peak SBP. DM, office SBP and age are independent predictors of HRE.