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NCT Number: NCT07021690

The Steno Opti-Bolus-Timing Studies

The project investigates the significance of the timing of insulin dosing for breakfast and lunch with an automated insulin pump and whether it matters if the meal primarily contains high or low glycemic index carbohydrates.

We hypothesise that a bolus given 15 minutes before the meal will result in the best blood glucose levels after the meal, regardless of the type of carbohydrates.

Participants will attend 6 experimental days over a maximum of 3 months, where they will be served either breakfast or lunch at the research site, depending on sub-study (breakfast or Lunch sub-study). Three different bolus timings will be tested, with either rapidly absorbed carbohydrates or slowly absorbed carbohydrates, in a randomized order for each participant. Participants will take insulin for the meal using the bolus calculator in the pump, either 15 minutes before, at the start of the meal, or 30 minutes after the meal. The development in sensor glucose will then be monitored for up to 4 hours after the meal.

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Key information

Conditions

Type 1 Diabetes (T1D) Autoimmune Diseases Diabetes Mellitus Diabetes Mellitus, Type 1 Endocrine System Diseases Glucose Metabolism Disorders Immune System Diseases Metabolic Diseases Nutritional and Metabolic Diseases

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Steno Diabetes Center Copenhagen Clinical Translational Research, Diabetes Technology

Herlev, DK-2730, Denmark

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Type 1 diabetes ≥ 3 years Age 18-70 years User of the MiniMed 780G for at least 3 months Use of Novorapid insulin in the pump (for a minimum of two weeks) TIR > 70% for minimum of 14 days Use carbohydrate counting and bolus calculation Uploads insulin pump and CGM data to the Carelink Personal database Pump settings: carbohydrate ratio (300-500 rule), active insulin time of ≤ 3 hours and smartguard target glucose of 5.5 or 6.1 mmol/L

Exclusion criteria

Use of anti-diabetic medicine (other than insulin), corticosteroids or other drugs affecting glucose metabolism during the study period or within 4 weeks prior to study start Diagnosed with gastroparesis Females who are pregnant, breast-feeding Food allergies related to standardized meals Alcohol or drug abuse Inability to understand the individual information and to give informed consent.

Current participation in another clinical trial that, in the judgment of the principal investigator, will compromise the study results

Treatment and study plan

High glyceamic index meal

Other

Meal sizes are standardized regarding the amount of carbohydrate, always 50 g. The composition of these meals focuses on selecting carbohydrates with high glycemic index.

Low glyceamic index meal

Other

Meal sizes are standardized regarding the amount of carbohydrate, always 50 g. The composition of these meals focuses on selecting carbohydrates with low glycemic index.

Primary outcomes

  1. Change in SG between three meal bolus delivery times for meals with two levels of glycemic index

    Time frame: From -15 min before the meal to 270 min after meal intake

    The primary objective is to compare the change in SG (from -15 min before the meal to the highest SG level measured during 0-270 min after start of meal intake) between three meal bolus delivery times for meals with two levels of glycemic index (GI) (high-GI and low-GI meals, respectively).

Secondary outcomes

  1. Area under the post-meal CGM-curve

    Time frame: From -15 min before the meal to 270 min after meal intake

  2. Difference in amount of insulin given for autocorrections during the post-meal period between the three bolus methods for each type of meal.

    Time frame: From -15 min before the meal to 270 min after meal intake

  3. Distribution of Time Below Range (TBR)

    Time frame: From -15 min before the meal to 270 min after meal intake

    Distribution of TBR in the observation period of 4 hours and 45 minutes around the meal between the three bolus methods for each GI meal.

  4. Difference in the number of Time Below Range events (with SG< 3.9 mmol/l)

    Time frame: From -15 min before the meal to 270 min after meal intake

    Difference in the number of Time Below Range (TBR) events (with SG< 3.9 mmol/l) in the observation period of 4 hours and 45 minutes around the meal between the three bolus methods for each GI meal.

  5. Distribution of Time In target Range (TIR)

    Time frame: From -15 min before the meal to 270 min after meal intake

    Distribution of Time In target Range (TIR) in the 4 hours and 45 minutes observation period around the meal between the three bolus methods for each GI meal.

  6. Distribution of Time In Tight target Range (TITR)

    Time frame: From -15 min before the meal to 270 min after meal intake

    Distribution of Time In Tight target Range (TITR), in the 4 hours and 45 minutes observation period around the meal between the three bolus methods for each GI meal.

  7. Distribution of Time Above Range (TAR)

    Time frame: From -15 min before the meal to 270 min after meal intake

    Distribution of Time Above Range (TAR), in the 4 hours and 45 minutes observation period around the meal between the three bolus methods for each GI meal.

  8. Number of hypoglycemia events (PG< 3.9 mmol/L )

    Time frame: From -15 min before the meal to 270 min after meal intake

Study contacts

Contact information is provided by the study sponsor or research team.

Ajenthen Ranjan, MD, PhD

CONTACT

[email protected]

+45 39680800

Karen Rytter, RN, PhD

CONTACT

[email protected]

+45 39680800

Sponsors and collaborators

Lead sponsor

Steno Diabetes Center Copenhagen

Other

Registry information

Official study title

Timing Insulin for Meals Using AID Systems

Acronym: OBT Studies

Important dates

Study start
2025
Primary completion
2026
Study completion
2027
First posted
Jun 15, 2025
Registry last updated
Jun 15, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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