Tirzepatide is a medication that is given as a liquid injection under the skin using a pre‑filled pen. In this study participants will receive it once a week. The drug is being tested to see if it can improve blood sugar control better than a placebo in adults who have type 1 diabetes and are overweight or obese. Researchers will also watch for any safety concerns while participants take the medication over a long period.

Obesity – A condition in which a person has an excess amount of body fat, usually defined by a body‑mass index (BMI) of 30 or higher. It develops gradually when the amount of calories taken in consistently exceeds the amount used for energy. Over time, the extra calories are stored as fat, leading to steady weight gain. As the body adapts, losing the added weight can become increasingly difficult. The condition often persists and may become more pronounced if the imbalance continues.

Overweight – A state where a person’s body weight is higher than what is considered normal, typically indicated by a BMI between 25 and 29.9. It arises when energy intake is slightly higher than energy expenditure. Weight usually increases slowly, adding extra fat around the body. If the excess calorie intake continues, the condition can progress to obesity.

Type 1 diabetes – A disease in which the pancreas stops producing enough insulin, a hormone needed to move sugar from the blood into cells. It most often begins in childhood or early adulthood. Without sufficient insulin, blood sugar levels rise and remain high. Over time, the body’s ability to regulate glucose becomes increasingly impaired. The condition typically remains stable but may require ongoing adjustments as the body changes.