The purpose of the study is to demonstrate safety and feasibility of a decision support system aimed at improving activity-related insulin boluses in Type 1 Diabetes.

Subjects with Type 1 diabetes often need to adjust insulin boluses for activity since activity may increase the chance of hypoglycemia. The aims of this study is to make better bolus decisions by integrating knowledge about daily physical activity (PA) into bolus decisions. It is expected to decrease risk of hypoglycemia related to previous PA and provide better glucose control. The idea is to first obtain a carbohydrate ratio that is optimized around the everyday activity level of the patient and then adjust boluses when the activity for the day is different (above or below) than their regular activity level.

Inclusion Criteria:

1. Type 1 Diabetes for at least one year
2. Using an insulin pump for at least 6 months
3. Age 18-65
4. Uses insulin parameters such as carbohydrate ratio and correction factors consistently on the insulin pump in order to dose insulin for meals or corrections
5. Access to internet and willing to upload data during the study
6. Willingness to maintain consistent activity regimen for 28 day collection period
7. Females, not currently known to be pregnant. If female and sexually active, must agree to use a form of contraception to prevent pregnancy while participating in the study. A negative urine/blood pregnancy test will be required for all women of child bearing potential. Subjects who become pregnant will be discontinued from the study.
8. Demonstration of proper mental status and cognition for the study.
9. An understanding of and willingness to follow the protocol and sign the informed consent.

Exclusion Criteria:

1. Diabetic ketoacidosis (DKA) in the 6 months prior to enrollment.
2. Severe hypoglycemia resulting in seizure or loss of consciousness in the 6 months prior to enrollment.
3. Pregnancy and intent to become pregnant during trial.
4. Use of acetaminophen is not allowed when CGM is in use
5. Use of non-insulin medications intended to lower glucose (e.g. glucagon-like peptide [GLP]-1 agonists, metformin)
6. Currently uses a clearly defined method for insulin bolusing to compensate for significant activity (e.g. marathon runner who uses temporary basal rates routinely and has separate basal profiles to account for exercise)
7. Inability to be physically active for more than 30 minutes per day.
8. Current enrollment in another intervention clinical trial.