How does dietary protein, when combined with carbohydrate, influence postprandial glucose levels in individuals with type 1 diabetes mellitus?

INTERVENTION: Participants with type 1 diabetes using intensive insulin therapy will be recruited. There will be a lead in period of one week before commencement of the study. This will allow researchers to contact particpants on a daily basis to review blood glucose levels and make any necessary adjustments to insulin doses. This will ensure optimal glycaemic control for the study period. On the day prior to the study a continuous glucose monitor (CGM) will be inserted to measure interstitial glucose levels for the duration of the study (6 days). The CGM will be blinded for the duration of the study. Over a period of 6 days, participants will consume a standard evening meal of no more than 60 grams of carbohydrate and low fat, low protein. Participants will give an insulin bolus as per usual management. Approximately 4 hours after each evening meal, participants will consume a test meal as supper, consisting of a protein drink (containing protein in amounts of 0g, 12.5g, 25g, 50g, given in randomised order) mixed with 30g of carbohydrate. There will be 2 evenings of glucose only drinks in amounts of 30g and 50g glucose for comparison. Particpants will have insulin as per usual management for the 30g of carbohydrate. No further food or drink will be given (other than water) overnight unless the participant has an episode of hypoglycaemia (blood glucose < 3.5 mmol/L or becomes symptomatic). Interstitial glucose levels will be measured for the next 8 hours following consumption of the test meal drink. The study will cease after the sixth night and the CGM will be removed. Participants will be contacted daily by phone to assess progress with the study and a food, activity and blood glucose diary will be kept by participants to ensure adherance to the protocol. CONDITION: Type 1 diabetes mellitus PRIMARY OUTCOME: The primary outcome is the mean glucose excursion from the consumption of the test meal, measured at 30 minute intervals, up to 300 minutes. Glucose will be meaured using continuous glucose monitoring (CGM) which measures interstitial glucose levels continually, sending updated readings to a small reciever every 5 minutes. At the end of the study period the reciever will be uploaded to a computer data base, allowing for analysis of the glucose measurements after each test meal. SECONDARY OUTCOME: Secondary outcome will be the velocity of the glucose rise following consumption of the test meal. ; The glucose rise will be measured using CGM overnight following consumption of the test meal. At the end of the study the CGM receiver will be uploaded to a computer data base where the data can be analysed and a graph produced to display the mean velocity of the glucose rise. INCLUSION CRITERIA: Type 1 diabetes for at least 12 months HbA1c 8.0% or less BMI < 97th centile Using intensive insulin therapy (multiple daily injection therapy or insulin pump therapy)