Hypoglycaemia is a frequent occurrence in Type 1 diabetes mellitus (T1DM) patients following endurance exercise (Tsalikian et al., 2005). Interestingly, completion of a short sprint following endurance exercise significantly reduces the degree of post-exercise hypoglycaemia in T1DM patients (Bussau et al., 2006). However, the impact of prolonged intermittent high intensity exercise patterns on the post-exercise glucose responses of T1DM patients is unclear. The aim of this study was to compare the metabolic responses of T1DM patients following intermittent and continuous exercise. With local ethics committee approval and informed consent 9 non-diabetic (ND) and 9 T1DM patients participated in this study. Physical and physiological characteristics of ND and T1DM respectively were (mean±SD); age: 27±7, 35±12 years; body mass: 79±6, 84±12 kg; HbA1c: 5.3±0.3, 8.1±0.6 %; VO₂max: 48.3±8.8, 41.8±4.9 ml kg min^-1. After two preliminary visits participants completed two main 45 min exercise trials in a randomised order, an intermittent running protocol designed to simulate intermittent games play (INT, Nicholls et al., 2000) and a continuous treadmill run (CON) that matched the mean rate of oxygen consumption of INT. Venous blood samples (10 ml) were taken at rest and for 3 h post-exercise to determine blood glucose and lactate concentrations. A continuous glucose monitor measured interstitial glucose concentrations for 24 h post-exercise. Data were analysed using a two-way ANOVA with post-hoc testing where appropriate and significance was established at P<0.05. The rate of oxygen consumption (expressed as a percentage of VO₂max) was similar between conditions (ND: CON 72±5, INT 73±5; T1DM: CON 77±8, INT 77±5 %, NS). Peak blood lactate concentrations were greater in INT compared with CON (INT: ND 6.8±3.0, T1DM 9.5±2.8 mM vs. CON: ND 1.9±0.8, T1DM 3.7±2.1 mM, P<0.05). Blood glucose concentration decreased significantly in T1DM compared to ND immediately after CON (ND 0.6±1.0 vs. T1DM -4.1±2.9 mM, P<0.05) and INT (CON 1.7±1.1 vs. T1DM -1.5±4.3 mM, P<0.05) and remained lower for 3 h post-exercise (P<0.05). Interstitial 24 h AUC glucose profiles were greater in T1DM compared to ND (T1DM: CON 2432±922, INT 2542±547 mM.24 h^-1 vs. ND: CON 1540±262, INT 1598±69 mM.24 h^-1, P<0.05) but there was no significant difference between INT or CON conditions within each group. The results demonstrate a significant reduction in blood and interstitial glucose concentrations of T1DM patients following both INT and CON exercise. However, there were no significant differences in glucose concentrations between the exercise types when performed at the same physiological intensity, despite a different anaerobic contribution. These data suggest the pattern of exercise does not influence the degree of post-exercise hypoglycaemia when the oxygen demand of exercise is similar.