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.

NCT07786064 | Completed

• 1 other identifier: 205/02.09.2024
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

The aim of this interventional clinical study is to compare the postprandial glycemic profile of patients with type 1 diabetes using either an open-loop (Medtronic Minimed 640G) or closed-loop (Medtronic Minimed 780G) insulin pump, after consuming a high-fat meal (pizza). The new advanced Medtronic MiniMed 780G insulin pump (closed hybrid loop) features an advanced algorithm that enables the automatic administration of corrective microdoses of insulin (microboluses) every 5 minutes. The open-loop pump offers the option of a dual-wave bolus pattern for insulin delivery, which is currently considered the best approach for managing such high-fat meals, a feature that is not available in the closed-loop pump. The main questions to answer are:

1. 1.To what extent can the new closed-loop insulin pump with automatic corrective microdoses of insulin manage the late postprandial hyperglycemia caused by a high-fat meal like pizza, which is extremely difficult for type 1 diabetes patients to manage?
2. 2.To what extent should protein and fat, in addition to carbohydrates, be accounted for in patients with type 1 diabetes using the closed-loop pump when consuming high-fat meals like pizza? Participants will be adults (\> 18years old) with type 1 diabetes using the MiniMed 780G pump (with either aspart or lispro insulin) and who are regularly followed up at the Insulin Pump Outpatient Department of the Diabetes Center of the Laiko General Hospital, National and Kapodistrian University of Athens Medical School, in Athens, Greece. They will undergo three study visits. During these visits, different strategies for managing a high-fat meal will be compared using both the closed-loop and open-loop modes of the insulin pump. A brief clinical history will be taken (duration of diabetes, conditions at initial diagnosis, treatment regimen, complications), and anthropometric measurements (height, weight, waist circumference) will be recorded. Data from the insulin pumps will be uploaded to a computer to document the pump's basic settings (insulin-to-carbohydrate ratio, insulin sensitivity factor, hourly basal rates, glucose target, active insulin time), and the most recent HbA1c value will be noted. The meal test will start only if the sensor glucose level upon arrival is below 180 mg/dL. An intravenous catheter will be placed in a forearm vein for repeated blood sampling to measure venous glucose levels at time 0 (pre-meal), 30, 60, 90, 120, 150, 180, 210, and 240 minutes after consuming the meal. At the same times, capillary blood glucose will also be measured, the glucose sensor readings from the pump will be recorded as well. The meal test will then begin, using different meal coverage approaches to be compared.

Conditions

Type 1 Diabetes Mellitus

Keywords

Diabetes Mellitus Type 1; Medtronic Minimed 780G; High-fat meal; carbohydrate-containing mixed meals

Outcome Measures

Primary Outcomes (1)

• Serum Postprandial Glucose Incremental Area Under the Curve (iAUC)(mg·h/dL)

  0-4 hours after consumption of the standardized meal

Study Arms (3)

open-loop dual-wave bolus, insulin increased by 50% for fat/protein, 50% upfront and 50% over 4h

OTHER

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

Other: Open-loop dual-wave bolus, with insulin dose increased by 50% for fat/protein and delivered 50% upfront, 50% over 4 h

closed-loop standard carbohydrate-based bolus

OTHER

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.

Other: Closed-loop standard insulin bolus strategy

closed-loop standard bolus plus 50% supplementary bolus 1 h after meal initiation

OTHER

Participants assigned to this sequence 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

Other: Supplementary insulin bolus strategy

Interventions

Closed-loop standard insulin bolus strategy OTHER

Participants receive the standard meal insulin bolus for a standardized pizza meal while using the MiniMed 780G advanced hybrid closed-loop system. The meal bolus is calculated according to each participant's individual insulin-to-carbohydrate ratio.The pump will deliver a single bolus of insulin 10 minutes before the meal.

closed-loop standard carbohydrate-based bolus

Supplementary insulin bolus strategy OTHER

Participants receive the standard meal insulin bolus for a standardized pizza meal while using the MiniMed 780G advanced hybrid closed-loop system, followed by a supplementary insulin bolus according to the predefined study protocol.

closed-loop standard bolus plus 50% supplementary bolus 1 h after meal initiation

Open-loop dual-wave bolus, with insulin dose increased by 50% for fat/protein and delivered 50% upfront, 50% over 4 h OTHER

The carbohydrate content of the meal 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. The meal bolus is calculated according to each participant's individual insulin-to-carbohydrate ratio.

open-loop dual-wave bolus, insulin increased by 50% for fat/protein, 50% upfront and 50% over 4h

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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%)

You may not qualify if:

• 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)

Sponsors & Collaborators

• Konstantinos Makrilakis, MD: lead

Study Sites (1)

Diabetes Laboratory, 1st Department of Propaedeutic Internal Medicine, National and Kapodistrian University of Athens Medical School, Laiko General Hospital, Athens, Greece

Athens, Athens, 11527, Greece

Location

Related Publications (5)

• Bell KJ, Fio CZ, Twigg S, Duke SA, Fulcher G, Alexander K, McGill M, Wong J, Brand-Miller J, Steil GM. Amount and Type of Dietary Fat, Postprandial Glycemia, and Insulin Requirements in Type 1 Diabetes: A Randomized Within-Subject Trial. Diabetes Care. 2020 Jan;43(1):59-66. doi: 10.2337/dc19-0687. Epub 2019 Aug 27.

  PMID: 31455688 BACKGROUND

• Bell KJ, Smart CE, Steil GM, Brand-Miller JC, King B, Wolpert HA. Impact of fat, protein, and glycemic index on postprandial glucose control in type 1 diabetes: implications for intensive diabetes management in the continuous glucose monitoring era. Diabetes Care. 2015 Jun;38(6):1008-15. doi: 10.2337/dc15-0100.

  PMID: 25998293 BACKGROUND

• Smith TA, Marlow AA, King BR, Smart CE. Insulin strategies for dietary fat and protein in type 1 diabetes: A systematic review. Diabet Med. 2021 Nov;38(11):e14641. doi: 10.1111/dme.14641. Epub 2021 Jul 18.

  PMID: 34251692 BACKGROUND

• Heinemann L. Insulin pump therapy: what is the evidence for using different types of boluses for coverage of prandial insulin requirements? J Diabetes Sci Technol. 2009 Nov 1;3(6):1490-500. doi: 10.1177/193229680900300631.

  PMID: 20144405 BACKGROUND

• Cavagnuolo L, Bozzetto L, Franco L, Costabile G, Riccardi G, Rivellese AA, Annuzzi G. Pizza Leavening Technique Influences Postprandial Glucose Response: A Randomized Controlled Trial in Patients With Type 1 Diabetes. Diabetes Care. 2019 Oct;42(10):e157-e158. doi: 10.2337/dc19-0778. Epub 2019 Aug 15. No abstract available.

  PMID: 31416896 BACKGROUND

MeSH Terms

Conditions

Diabetes Mellitus, Type 1

Interventions

FAT1 protein, human; Parturition

Condition Hierarchy (Ancestors)

Diabetes Mellitus; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases; Endocrine System Diseases; Autoimmune Diseases; Immune System Diseases

Intervention Hierarchy (Ancestors)

Pregnancy; Reproduction; Reproductive Physiological Phenomena; Reproductive and Urinary Physiological Phenomena

Study Officials

• Konstantinos Makrilakis, MD, PhD

  National and Kapodistrian University of Athens

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Professor of Internal Medicine

Model Details: The present study will be an open-label, randomized, controlled, cross-over intervention study involving persons with Diabetes Mellitus type 1. Participants will consume the same amount of a high-fat meal (pizza).

Study Record Dates

• First Submitted: August 21, 2026
• First Posted: August 25, 2026
• Study Start: June 30, 2025
• Primary Completion: December 15, 2025
• Study Completion: December 15, 2025
• Last Updated: August 25, 2026

Record last verified: 2026-08

Locations

GR (1)