A Phase 2 interventional study of Tirzepatide 2.5mg weekly and Placebo injection (normal saline) in Type 1 Diabetes Mellitus, sponsored by Victor Chang Cardiac Research Institute. Recruiting at 1 site in Australia. Open to participants aged 18 Years to 70 Years. Per ClinicalTrials.gov, last updated 2026-09-16.
Sponsored by Victor Chang Cardiac Research Institute · Phase 2, Interventional, and Treatment
This study will examine the effects of Tirzepatide (TZP), a glucagon-like peptide 1 (GLP1) - gastric inhibitory peptide (GIP) co-agonist, on metabolism in type 1 diabetes (T1D). Research participants with T1D will undergo measures of insulin sensitivity, and hormone levels post-meal, post-hypoglycemia and during the overnight period. These measures will be performed prior to, and after 6 weeks of treatment with TZP or placebo.
TIRTLE2 is a phase 2 double-blinded placebo-controlled mechanistic clinical trial that extends upon the findings of TIRTLE1, a phase 2 double-blinded placebo-controlled trial (TZP 5.0mg vs placebo over 12 weeks) in T1D (trial registration: ACTRN12624000111572).
TIRTLE2 is a designed to determine whether TZP can 1) improve whole body insulin sensitivity, 2) reduce prandial glucagon secretion, 3) impacts lipolysis and growth hormone secretion overnight, and 4) determine if TZP can maintain the glucagon response to hypoglycemia. The acute effects of TZP on metabolism will be assessed after 6 weeks, to limit the degree of weight loss (indicating a role for TZP on improving metabolic physiology in T1D, beyond weight management in T1D).
To address these research aims, a single comprehensive clinical trial will be performed in 44 participants with T1D, who will receive a weekly injection of TZP 2.5mg or placebo for 6 weeks. A short treatment duration was chosen to assess if TZP offers T1D-specific benefits prior to significant weight loss.
TIRTLE2 will employ the 'gold standard' hyperinsulinemic-euglycemic and hypoglycemic clamps, in conjunction with complementary analyses of the effects of TZP on metabolism across multiple physiological states. This mechanistic study will define mechanisms by which GLP1-GIP co-agonism may uniquely provide clinical benefits in T1D during the fasting and fed states, and during hypoglycemia.
3,754 studies on the registry are indexed under Diabetes Mellitus, Type 1; 600 are open to participants now.
This study's planned enrollment of 44 is close to the median of 40 across 2,820 interventional studies indexed under Diabetes Mellitus, Type 1.
Browse Diabetes Mellitus, Type 1 studies →This is the only study on the registry with Victor Chang Cardiac Research Institute as lead sponsor.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HbA1c
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Administered subcutaneously.
Drug: Tirzepatide 2.5mg weekly
Administered subcutaneously.
Drug: Placebo injection (normal saline)
Tirzepatide 2.5 mg/0.5 mL solution for injection vial or pre-filled pen. Each vial/ pre-filled pen contains tirzepatide 2.5 mg in 0.5 mL solution (2.5mg in 0.6mL if Kwikpen) Tirzepatide will be administered by drawing up into a syringe, then administering by subcutaneous injection weekly by study nurses.
Placebo will be given as 0.5mL normal saline (if comparator against vial or pre-filled pen), or 0.6mL (if comparator against Mounjaro Kwikpen), drawn up into a syringe and administered by subcutaneous injection weekly by study nurses.
Whole-body insulin sensitivity
Change in insulin sensitivity from baseline, assessed using the hyperinsulinemic-euglycemic clamp (60 mU/m2/min)
Time frame: 6 weeks
Prandial glucagon secretion
Change from baseline glucagon area under the curve (AUC) during mixed meal tolerance test (MMTT)
Time frame: 6 weeks
Glucagon response to hypoglycemia
Change from baseline glucagon AUC after glucose nadir as measured during the hyperinsulinemic hypoglycemic clamp
Time frame: 6 weeks
% Time level 2 hypoglycemia
Change from baseline % time level 2 hypoglycemia (defined by glucose \< 54 mg/dL \[\<3.0 mmol/L\]) as measured by continuous glucose monitoring
Time frame: 6 weeks
% Time level 1 hypoglycemia
Change from baseline % time level 1 hypoglycemia (defined by glucose \< 70 mg/dL \[3.9 mmol/L\] and ≥ 54 mg/dL \[3.0 mmol/L\]) as measured by continuous glucose monitoring
Time frame: 6 weeks
Resting energy expenditure (REE)
Change from baseline REE as measured by indirect calorimetry
Time frame: 6 weeks
Overnight growth hormone curve
Change from baseline growth hormone area under the curve (AUC) as measured overnight blood samples
Time frame: 6 weeks
Overnight free-fatty acids (FFA) curve
Change from baseline FFA under the curve (AUC) as measured overnight blood samples
Time frame: 6 weeks
Total daily insulin dose
Change from baseline total daily insulin dose as measured by pump record
Time frame: 6 weeks
Total daily basal insulin dose
Change from baseline total daily basal insulin dose as measured by pump record
Time frame: 6 weeks
Total daily bolus insulin dose
Change from baseline total daily bolus insulin dose as measured by pump record
Time frame: 6 weeks
% Time in Range (TIR)
Change from baseline %TIR (defined by % readings between 70mg/dL - 180 mg/dL \[3.9 - 10.0 mmol/L\]) as measured by continuous glucose monitoring
Time frame: 6 weeks
% Time Below Range (TBR)
Change from baseline %TBR (defined by % readings below 70mg/dL \[3.9mmol/L\]) as measured by continuous glucose monitoring
Time frame: 6 weeks
% Time level 1 hyperglycemia
Change from baseline % time level 1 hyperglycemia (defined by glucose \> 180 mg/dL \[10 mmol/L\] and glucose ≤ 250 mg/dL \[13.9 mmol/L\]) as measured by continuous glucose monitoring
Time frame: 6 weeks
% Time level 2 hyperglycemia
Change from baseline % time level 1 hyperglycemia (defined by glucose \> 250 mg/dL \[13.9 mmol/L\])) as measured by continuous glucose monitoring
Time frame: 6 weeks
Glycemic variability
Change from glycemic variability as measured by continuous glucose monitoring
Time frame: 6 weeks
Gastric emptying
Change from baseline gastric emptying during the mixed meal tolerance test (MMTT) assessed using radiolabelled isotope and breath sampling
Time frame: 6 weeks
Diabetes Treatment Satisfaction
Change from baseline diabetes treatment satisfaction, as measured by questionnaire (DTSQ)
Time frame: 6 weeks
Metanephrine response to hypoglycemia
Change from baseline peak metanephrine after glucose nadir as measured during the hyperinsulinemic hypoglycemic clamp
Time frame: 6 weeks
Normetanephrine response to hypoglycemia
Change from baseline peak normetanephrine after glucose nadir as measured during the hyperinsulinemic hypoglycemic clamp
Time frame: 6 weeks
Growth hormone response to hypoglycemia
Change from baseline peak growth hormone after glucose nadir as measured during the hyperinsulinemic hypoglycemic clamp
Time frame: 6 weeks
Cortisol response to hypoglycemia
Change from baseline peak cortisol after glucose nadir as measured during the hyperinsulinemic hypoglycemic clamp
Time frame: 6 weeks
Glucose requirement to correct hypoglycemia
Change from baseline glucose infusion requirement after glucose nadir to correct hypoglycemia during the hyperinsulinemic hypoglycemic clamp
Time frame: 6 weeks
Body weight
Change from baseline body weight as measured by scale
Time frame: 6 weeks
% fat free mass
Change from baseline % fat free mass as measured by air displacement plethysmography
Time frame: 6 weeks
% fat mass
Change from baseline % fat mass as measured by air displacement plethysmography
Time frame: 6 weeks
Lipid profile
Change from baseline lipid profile as measured by blood assay
Time frame: 6 weeks
Systolic blood pressure
Change from baseline systolic blood pressure as measured by digital sphygmomanometer
Time frame: 6 weeks
Diastolic blood pressure
Change from baseline diastolic blood pressure as measured by digital sphygmomanometer
Time frame: 6 weeks
Arterial stiffness
Change from baseline arterial stiffness as measured by Augmentation index (AIx) by radial artery tonometry
Time frame: 6 weeks
Arterial stiffness
Change from baseline arterial stiffness as measured by carotid femoral pulse-wave velocity (cfPWV)
Time frame: 6 weeks
Prandial GLP1 secretion
Change from baseline GLP1 area under the curve (AUC) during mixed meal tolerance test (MMTT)
Time frame: 6 weeks
Prandial GIP secretion
Change from baseline GIP area under the curve (AUC) during mixed meal tolerance test (MMTT)
Time frame: 6 weeks
Fasting glucagon
Change from baseline fasting glucagon level as measured by blood assay.
Time frame: 6 weeks
Fasting GLP1
Change from baseline fasting GLP1 as measured by blood assay
Time frame: 6 weeks
Fasting GIP
Change from baseline fasting GIP as measured by blood assay
Time frame: 6 weeks
Supraclavicular temperature profile
Change from baseline supraclavicular temperature profile as measured by temperature sensor
Time frame: 6 weeks
Diet composition
Change from baseline diet composition as measured by self-reported diet diary entries
Time frame: 6 weeks
Growth differentiation factor 15 (GDF15)
Change from baseline fasting GDF15 as measured by blood assay
Time frame: 6 weeks
Fasting liver function tests
Change from baseline fasting liver function tests as measured by blood assay
Time frame: 6 weeks
Pulse rate
Change from baseline pulse rate as measured by digital sphygmomanometer
Time frame: 6 weeks
C-terminal telopeptide of type 1 collagen
Change from baseline C-terminal telopeptide of type 1 collagen (CTX) as measured by blood assay
Time frame: 6 weeks
Procollagen type 1 N-terminal propeptide
Change from baseline procollagen type 1 N-terminal propeptide (P1NP) as measured by by blood assay
Time frame: 6 weeks
HbA1c
Change from baseline HbA1c as measured by blood assay.
Time frame: 6 weeks
Plan to share: Yes — Data from these analyses can be made available upon the condition of compliance with institutional review board restrictions and a data sharing agreement with the project sponsor. We encourage researchers who propose use of study data to contact the study PI.
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Studies of the drug tested here: Tirzepatide