Does the Type of Dietary Protein affect Postprandial Glycaemia in Type 1 Diabetes?

INTERVENTION: Relationship Between Type of Dietary Protein and Postprandial Glycaemia A randomised, within‐subject trial comparing capillary postprandial glycaemia for meals of varying types of protein over 5h with the same insulin dose for all meals (based on the insulin: carbohydrate (CHO) ratio) in 20 adults with T1D using insulin pump therapy. Dietary Protein: * 5 different types of protein (beef, chicken, egg, salmon and whey protein isolate) added to 45g CHO Design Rationale: This study will establish the relationship between type of protein and glycaemia for 5 different types of protein. Current literature in type 1 diabetes primarily relies on studies conducted using whey isolate, a particularly potent insulin secretagogue. Studies in other populations suggest that different sources of protein have differential effects. This study will therefore use commonly consumed protein sources to reflect realistic meals. Test Meals & Insulin Doses Insulin doses calculated using participants’ insulin: CHO ratio (standard clinical practice). Test Meal A: 30g protein with 45g of CHO (beef with rice) Test Meal B: 30g protein with 45g of CHO (chicken with rice) Test Meal C: 30g protein with 45g of CHO (eggs with rice) Test Meal D: 30g protein with 45g of CHO (salmon with rice) Test Meal E: 30g protein with 45g of CHO (whey protein isolate with rice) Wash out period: All test sessions must be completed on separate days but may be consecutive days. Study Procedure: Participants will be instructed to avoid alcohol and exercise for 24h prior to the session and not make any manual insulin adjustments (correction bolus or temporary basal rate) after midnight. Participants will be instructed to fast from midnight, with only water allowed. In the case of hypoglycaemia, participants will be instructed to treat their hypoglycaemia according to their usual clinical care and their test session will be rescheduled. On the day of the test session, participants will arrive at the metabolic kitchen at the Charles Perkins Centre, University of Sydney between 7:00‐ 9:00am after an overnight fast. The fasting BGL must be between 4‐10 mmol/L for the session to be commenced. If eligible, capillary blood samples will be taken 30, 15 and 0 minutes prior to the consumption of the test meal. The allocated insulin dose will be administered subcutaneously via an insulin pump by the CDE 15 minutes immediately prior to the consumption of the test meal. The test food will be served with 250mL of plain water and participants will be given 12 minutes to consume both the food and water and then no other food or drink will be provided for the remainder of the 5h test session (except water). Capillary blood samples will be collected at 15 min, 30 min, 45 min, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h and 5h. If hypoglycaemia occurs (> 3.5 mmol/L), the test session will be terminated, the event recorded and the participant treated appropriately. Subjective satiety will be assessed using a 17‐point likert scale. CONDITION: Type 1 Diabetes PRIMARY OUTCOME: Differences in 5hr iAUCglucose SECONDARY OUTCOME: Coefficient of Variation in blood glucose levels Incidence of hypoglycaemia (< 3.5mmol/L) J‐Index of blood glucose levels Mean Amplitude of Glycaemic Excursion (MAGE) Mean postprandial blood glucose level Satiety Standard deviation around mean postprandial blood glucose level INCLUSION CRITERIA: Aged 18‐70y, T1D diagnosed for greater than or equal to 1 year, insulin pump therapy for greater than or equal to 3 months, HbA1c less than or equal to 8.5% (69 mmol/mol), reliably performing self‐monitoring of blood glucose at least four times daily/or using continuous glucose monitoring and fluency in English.