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NCT Number: NCT06180616

Tirzepatide for the Treatment of Concurrent Type 1 Diabetes and Overweight or Obesity

This study is a 2-arm, double blinded, randomised clinical trial where 40 participants will be assigned 1:1 to insulin treatment alone (control) or insulin treatment and tirzepatide treatment for 32 weeks. The primary objective is to demonstrate that tirzepatide treatment, dose incremented to 15mg QW for 32 weeks adjunctive to insulin treatment can reduce body weight in patients with T1D and overweight or obesity when compared to insulin treatment alone. The secondary objective is to demonstrate that tirzepatide treatment, dose incremented to 15mg QW for 32 weeks can improve glycaemic control (measured by hbA1c), improve time in range, reduce insulin requirements, and reduce the severity of comorbidities in people with obesity and T1D. This trial includes a 6 month follow-up period.

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Key information

Conditions

Type 1 Diabetes Mellitus Autoimmune Diseases Body Weight Diabetes Mellitus Diabetes Mellitus, Type 1 Endocrine System Diseases Glucose Metabolism Disorders Immune System Diseases Metabolic Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Overweight and Obesity Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Age 18-70 years at screening
  • A clinical diagnosis of T1D for at least 12 months at time of screening
  • Body mass index ≥ 27kg/m2
  • HbA1c ≤ 10%
  • Capable and willing to self-inject tirzepatide once per week
  • In women of childbearing potential, a negative pregnancy test and willing to use effective contraception consistently for the duration of the study
  • Able and willing to provide written informed consent for study participation
  • Able and willing to use Easy Diet Diary
  • Able and willing to keep an exercise log
  • Willing to share devices data uploads
  • Has current glucagon product to treat severe hypoglycaemia
  • Has current ketone meters to check ketones

Exclusion criteria

  • Age <18 years and >70 years
  • A clinical diagnosis of diabetes type other than T1D
  • HbA1c > 10%
  • Use of GLP-1 receptor agonist within 1 month of study screening
  • Use of any glucose lowering medications aside from insulin within 1 month of study screening
  • History of hypersensitivity to investigational medicinal product or related product
  • Obesity that is induced by other endocrine disorders
  • Pregnancy or positive pregnancy test at time of screening, or unwilling to use effective contraception consistently for the duration of the study which is defined in Appendix 1
  • Active proliferative diabetic retinopathy, maculopathy, or severe no proliferative diabetic retinopathy requiring acute treatment
  • Known gastric emptying abnormality
  • History of chronic or acute pancreatitis, uncontrolled hypertension, acute cardiovascular condition within 3 months
  • No longer than 12 months of insulin treatment
  • Not willing to use a NovoPen 6 to record insulin dosing if currently using multiple daily injections
  • Insulin pump, CGM or smart phone devices are not compatible for data transfer
  • Not willing to share device data
  • Current use of any steroidal medication, or planned long-term steroidal treatment (>4 weeks) during the study period
  • Serum triglycerides >500 mg/dL
  • History of or plans for bariatric surgery during the study period
  • eGFR <45 ml/min/1.73 m2
  • History of severe hypoglycaemia (within 3 months of trial period)
  • History of diabetic ketoacidosis (within 3 months of trial period)
  • History of stroke (within 3 months of trial period)
  • History of heart failure
  • Planned coronary, carotid, or peripheral artery revascularisation
  • History of acute or chronic liver disease
  • History of allergy to any form of insulin, GLP-1RA or its excipients
  • History of malignancy requiring chemotherapy, surgery, or radiation (within 5 years of trial period)
  • History of multiple endocrine neoplasia type 2, familial thyroid cancer, or non-familial medullary thyroid cancer
  • Presence or history of malignant neoplasms or in situ carcinomas (other than basal or squamous cell skin cancer, low-risk prostate cancer, or in situ carcinomas of the cervix or carcinoma in situ/high grade prostatic intraepithelial neoplasia) within 5 years before screening
  • Have a pacemaker, or metal implants
  • Participation in other intervention trials during the study period
  • Existence of any additional health conditions or medical issues, including significant psychiatric disorders, that render a person unfit for the study at the discretion of the investigators

Treatment and study plan

Tirzepatide

Drug

Tirzepatide will be self-administered subcutaneously by study participants via an injection. The drug will be taken weekly following the schedule: 4 weeks at 2.5 mg QW, 4 weeks at 5.0 mg QW, 4 weeks at 7.5 mg QW, 4 weeks at 10.0 mg QW, 4 weeks at 12.5 mg QW, 12 weeks at 15 mg QW.

Modification of study drug will be performed if the participant is experiencing significant side effects and cannot tolerate the higher dosage of the study drug. In this instance, the study drug dosage will be reduced to the previously tolerated dosage and held at this dose for a further 4 weeks. One further attempt at dose escalation will be undertaken after 4 weeks, at the discretion of the participant and the study investigator. If recurrent side effects are experienced by the participant, the study drug will be returned to the previously tolerated dosage, and the prescription continued at this dosage for the remainder of the study.

Primary outcomes

  1. Body weight

    Time frame: 32 weeks

    Percent body weight change (%)

Secondary outcomes

  1. hbA1c

    Time frame: 32 weeks

    Change in hbA1c levels (%)

  2. Time in range

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (time in range (3.9-10mmol/L))

  3. Total daily insulin dose

    Time frame: 32 weeks

    Change in insulin dose (total daily dose, units/kg of body weight)

  4. Insulin carbohydrate ratio

    Time frame: 32 weeks

    Change in insulin dose (insulin carbohydrate ratio (units per g))

  5. Waist and neck circumference

    Time frame: 32 weeks

    Change in waist and neck circumference

  6. Blood pressure

    Time frame: 32 weeks

    Change in blood pressure

  7. Mean glucose

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (mean glucose)

  8. Time in hypoglycaemia

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (time in hypoglycaemia (mild < 3.9, severe < 2.5mmol/L))

  9. Time in hyperglycaemia

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (time in hyperglycaemia (mild >10, severe 13.9mmol/L))

  10. Continuous glucose monitoring

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (SD)

  11. Continuous glucose monitoring

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (CV)

  12. Continuous glucose monitoring

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (CONGA)

  13. Continuous glucose monitoring

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (J-index)

  14. Continuous glucose monitoring

    Time frame: 32 weeks

    Change in continuous glucose monitoring (CGM) metrics (MAGE)

  15. Total cholesterol

    Time frame: 32 weeks

    Change in lipid parameters (total cholesterol)

  16. Triglyceride

    Time frame: 32 weeks

    Change in lipid parameters (triglyceride)

  17. LDL-C

    Time frame: 32 weeks

    Change in lipid parameters (LDL-C)

  18. HDL-C

    Time frame: 32 weeks

    Change in lipid parameters (HDL-C)

  19. ACR

    Time frame: 32 weeks

    Change in albumin to creatinine ratio (ACR)

  20. eGFR

    Time frame: 32 weeks

    Change in renal function (eGFR)

  21. HSI

    Time frame: 32 weeks

    Change in NAFLD biomarker HSI. Hepatic steatosis defined as HSI > 36

  22. FIB-4

    Time frame: 32 weeks

    Change in NAFLD biomarker FIB-4. Hepatic steatosis defined as FIB-4 index ≥ 1.3 or < 1.3

  23. Brachial-Ankle Pulse Wave Velocity using Ankle Brachial Index Machine

    Time frame: 32 weeks

    Change in Brachial-Ankle Pulse Wave Velocity (baPWV)

  24. Arterial Stiffness using a Pulse Wave Tonometer

    Time frame: 32 weeks

    Change in arterial stiffness

  25. Aortic Stiffness using a Pulse Wave Tonometer

    Time frame: 32 weeks

    Change in aortic stiffness

  26. Left Ventricular Strain using Electrocardiogram

    Time frame: 32 weeks

    Change in left ventricular strain

Sponsors and collaborators

Lead sponsor

Royal North Shore Hospital

Other

Registry information

Official study title

Tirzepatide for the Treatment of Concurrent Type 1 Diabetes and Overweight or Obesity: A Placebo-Matched Randomised Controlled Trial

Acronym: TZP-T1D

Important dates

Study start
2026
Primary completion
2028
Study completion
2028
First posted
Dec 22, 2023
Registry last updated
Jul 29, 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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