BACKGROUND: Slow spaced eating is associated with improved satiety and gut hormone responses in normal-weight participants. This crossover study compared the effect of slow and rapid eating patterns on hunger, fullness, glucose, insulin, and the appetite-related gut hormones peptide YY (PYY), glucagon-like peptide-1 (GLP-1), and ghrelin in overweight and obese participants with type 2 diabetes mellitus (T2DM). METHODS: 20 overweight and obese participants with T2DM on metformin were recruited. A test meal of 300 mL ice-cream was consumed in random order in two different sessions by each participant; meal duration was 5 or 30 min. Fullness and hunger as assessed by visual analog scales (VAS), and glucose, insulin, PYY, GLP-1, and ghrelin were measured at baseline and at 30 min intervals after meal termination for 3 h. RESULTS: Fullness VAS ratings were significantly higher at the 90', 120', 150', and 180' time points and hunger ratings were lower at 90', 150', and 180' for the 30 min meal. The area under the curve (AUC) for fullness was higher after the 30 min meal than after the 5 min meal (11 943.7±541.2 vs 10 901.0±568.8 mm min, p=0.003) whereas the hunger AUC was lower (4442.9±328 vs 4966.7±347.5 mm min, p=0.012). There were no differences in glucose, insulin, PYY, GLP-1, and ghrelin responses. CONCLUSIONS: Slow spaced eating increased fullness and decreased hunger ratings in overweight and obese participants with T2DM, without the improvement in gut hormone responses found in normal-weight participants. Slow spaced eating may be a useful prevention strategy, but might also help curb food intake in those already suffering from obesity and diabetes.