Comparative Study of the Postprandial Glycemic Profile After Consumption of a High-fat Meal (Pizza) Between the Open-loop System (Medtronic MiniMed 640G) and the Hybrid Closed-loop System (Medtronic MiniMed 780G) in Patients With Type 1 Diabetes Using Continuous Subcutaneous Insulin Infusion Pumps.

Participants will consume a total of 250 g of pizza, (a "four cheese" type pizza with classic crust) with the following macronutrient composition by percentage: 37.9% fat, 41.07% carbohydrates and dietary fiber, and 21.01% protein, and it must be consumed within 10 minutes, with or without water. One tablespoon of olive oil will be added to the above meal to increase its fat content. After the addition of olive oil, the final meal composition in macronutrients will be as follows: 41.25 g fat (48.62% & 366.25 kcal), 64 g carbohydrates (33.98% & 256 kcal) and 32.75 g protein (17.39% & 131 kcal. During the three different study visits, three different meal consumption management approaches will be applied. Given the ability of the 780G insulin pump to operate as a 640G pump, this enables a direct comparison of different fat-rich meal management approaches in the same patients using only one type of pump. In the first study visit, involving dual-wave insulin bolus in open-loop conditions, patients will exit the automatic mode of the 780G pump immediately prior to the meal test and enter open-loop mode using the pump as a 640G. The carbohydrate content of the meal (64 g) will be declared, and the meal insulin dose will be increased by 30% for fat and 20% for protein, a total increase of 50%. The dual-wave bolus pattern of insulin delivery will be used: 50% of the recommended dose will be given 10 minutes before the meal, and the remaining 50% will be delivered as an extended bolus over the next 4 hours. In the second study visit, involving a single insulin bolus in closed-loop conditions, only the carbohydrate grams of the meal will be declared (as fat and protein are not recommended to be included in the bolus calculation with the 780G pump). The pump will deliver a single bolus of insulin 10 minutes before the meal. In the third visit, participants will receive the same predetermined amount of pizza in closed-loop conditions. Ten minutes before the meal, 64 g of carbohydrates will be declared, and 1 hour after the meal has started, the insulin dose will be increased by 30% for fat and 20% for protein, a total of 50%, calculated based on 50% of the carbohydrate grams declared before the meal. The total and cumulative areas under the curve (AUC), reflecting postprandial glycemic levels for up to 4 hours post-meal, will be calculated and compared across the three approaches using non-inferiority statistical analysis. Additionally, sensor glucose data (measured every 5 minutes) will be collected for a total of up to 8 hours post-meal, to capture any differences in late postprandial hyperglycemic peaks. All participants will receive detailed verbal and written information about the study procedures and objectives and will sign an informed consent form.

Inclusion criteria

• Diagnosis of Type 1 Diabetes (T1D) at least 12 months prior to study participation
• Use of continuous subcutaneous insulin infusion (CSII) pump for at least 6 months prior to enrollment ("trained" patients)
• Adequate glycemic control (recent HbA1c value ≤ 8%)

Exclusion criteria

• Known microvascular and macrovascular complications of diabetes
• History of gastroparesis or malabsorption
• History of stomach or intestinal surgery
• Use of medications that affect gastrointestinal motility (e.g., prokinetics, antiemetics, GLP-1 agonists, etc.)
• Known deficiency of fat-soluble vitamins (A, D, E, K)