Background: Insulin detemir is long-acting insulin analog that is weight-neutral compared with other long-acting insulins in patients with type 1 diabetes. One mechanism for this may be an effect of insulin detemir to enhance satiety. We hypothesized that type 1 diabetes patients on insulin detemir will eat fewer calories when presented with a standardized buffet meal following a 24-hour fast as compared to those on insulin glargine. Methods: Ten subjects with C-peptide negative type 1 diabetes participated in a randomized, double-blind crossover study in which they received equivalent doses of either insulin detemir or insulin glargine twice daily for at least 3 weeks. They were subsequently admitted to the UNM Clinical Research Unit for a 24-hour fast, after which they were allowed to eat to satiety from a standardized buffet. Caloric consumption, hunger score and body compositions were measured. Leptin, Ghrelin and Peptide YY were assessed at baseline, after 24-hour fast, and after ingestion of the meal. Results: Subjects were aged 35±11 years, had diabetes for 18±11 years, had A1c levels of 8±1% and BMI of 30±8 kg/m2. Short acting insulin doses were higher for subjects receiving insulin detemir versus insulin glargine (p<0.001). Hunger scores, total energy ingested following the 24-hour fast, and Resting Energy Expenditure did not significant differ between the two study conditions. Conclusion: The weight-neutrality of insulin detemir in type 1 diabetes is not attributable to reduced caloric intake following a fast, or to serum satiety factors.