Experience with Roux-en-Y gastric bypass in patients with type 1 diabetes is very limited, despite an increasing prevalence of obesity also in this population. We describe changes in anthropometric measures, insulin dose, HbA1c, blood pressure, lipid status, and metabolic response to a liquid mixed meal throughout the first year after RYGB in an obese patient with type 1 diabetes. No change in HbA1c was observed, but a 48% reduction in weight-adjusted insulin dose and improvements in cardiovascular risk factors was seen 1 year after surgery. Exaggerated secretions of anorexigenic gut hormones were seen during the meals.