TIRTLE1 low-dose tirzepatide in adults with T1D and obesity
Completed Australian phase-2 randomized trial of low-dose weekly tirzepatide versus placebo alongside insulin. It found a large 12-week weight and insulin-dose signal, but was too small and short to establish durable glycemic benefit or uncommon safety risks.
Primary endpoints
- Change in body weight at 12 weeks
Results so far
Twenty-four adults were randomized and 22 completed the May-December 2024 study. At 12 weeks, the adjusted weight difference was -8.7 kg (95% CI -12.0 to -5.5; P<0.0001), equivalent to 8.8% body-weight loss versus placebo. Total daily insulin fell 35.1% relative to placebo. HbA1c differed by -0.4 percentage points (95% CI -0.7 to 0.0; P=0.05), while time in range and time below range did not differ significantly. There was no DKA, severe hypoglycemia, or serious adverse event; nonserious events occurred in 75% on tirzepatide versus 8.3% on placebo, mostly gastrointestinal. The trial was powered for weight, not glycemia or safety, and lasted only 12 weeks.