The purpose of this study is to evaluate an insulin bolus for use to cover higher fat meals.

Subjects will have several admissions during which the investigators will apply an iterative dose escalation protocol to derive an optimized insulin bolus dose (carbohydrate-to-insulin ratio for fat to minimize postprandial hyperglycemia following higher fat meals. The investigators hypothesize that the incremental insulin dose required to cover dietary fat in patients with type 1 diabetes will be related to total daily insulin dose (U/kg).

Subjects for this study will be adults with type 1 diabetes who use an insulin pump for diabetes self-management.

Subjects will be admitted to the clinical research center in the morning in the fasting state. Subjects will have several admissions. During the initial two admissions, subjects will receive either pizza-low fat or pizza-high fat, covered with insulin doses calculated from their usual insulin-to-carbohydrate ratio. Study subjects in whom the bolus did not provide adequate insulin coverage for pizza-high fat will then undergo an additional 1-5 admissions during which they will receive the pizza-high fat meal with progressively increasing insulin doses until ≥ 90% of all postprandial glucose values are within the target range 80-180 mg/dL.

Inclusion Criteria:

• Adult patients (aged 18-75 years) with type 1 diabetes > 3 years, on insulin pump therapy.

Exclusion Criteria:

• History or symptoms suggestive of gastroparesis or gastric dysmotility; History of celiac disease, pancreatic exocrine dysfunction or other conditions that cause malabsorption or maldigestion; Eating disorder; Diet allergies; Special diet restrictions, such as vegan; Medications know to affect insulin sensitivity (such as glucocorticoids) or affect gastrointestinal motility (such as reglan); High-titre insulin autoantibodies with delayed insulin kinetics; Women who are breast feeding, pregnant, or wanting to become pregnant.