Context:Pancreatic atrophy is common in longstanding type 1 diabetes, but there are limited data concerning pancreas size at diagnosis.Objective:Our objective was to determine whether pancreatic size was reduced in patients with recently diagnosed type 1 diabetes and assess whether pancreatic volume was related to residual β-cell function or islet autoantibodies.Design and Setting:We conducted a controlled cohort study with strict inclusion criteria, recruiting from hospital diabetes clinics between 2007 and 2010.Patients and Healthy Controls:Participants included 20 male adult patients (median age 27 yr) with recent-onset type 1 diabetes (median duration 3.8 months) and 24 male healthy controls (median age 27 yr).Intervention:Interventions included noninvasive magnetic resonance imaging, collection of fasting blood samples, and glucagon stimulation testing in patients.Main Outcome Measures:We compared pancreatic volume estimates between patients with recent-onset type 1 diabetes and healthy controls as planned a priori.Results:Scans were analyzed by an experienced radiologist blinded to diabetes status. Pancreatic volume correlated with body weight in patients and controls (P = 0.007). After adjustment for body weight, mean pancreatic volume index was 26% less in patients (1.19 ml/kg, se 0.07 ml/kg) than in controls (1.61 ml/kg, se 0.08 ml/kg) (P = 0.001). No correlation was seen between pancreatic volume index in patients and diabetes duration, glucose or C-peptide levels, glycated hemoglobin, and islet autoantibodies.Conclusions:Pancreatic volume is reduced by 26% in patients with type 1 diabetes within months of diagnosis, suggesting that atrophy begins years before the onset of clinical disease. Pancreatic atrophy within individuals is therefore a potential clinical marker of disease progression.