Study of Antithymocyte Globulin for Treatment of New-onset T1DM

Type 1 diabetes mellitus (T1DM) is an autoimmune disease in which the immune system mistakenly attacks the insulin-producing beta cells in the pancreas. Without these cells, the body cannot maintain proper blood glucose levels in response to daily activities, such as eating or exercise. Generally, at the time someone is diagnosed with T1DM, not all of a person's beta cells have been destroyed - between 15-40% remain healthy and are still able to produce insulin. Importantly, even small amounts of naturally produced insulin can improve blood sugar control, make daily management of diabetes less complicated, and reduce the risk of long term complications. Preserving the remaining precious beta cells is therefore the goal of the START trial. The medication being tested in the START trial is antithymocyte globulin (e.g., Thymoglobulin®), a mixture of specialized proteins called antibodies. ATG attaches itself to white blood cells known as T cells, some of which are responsible for the immune system's attack on beta cells that occurs in T1DM. ATG can change how T cells work, and can eliminate a large proportion of the T cells from the bloodstream temporarily. Treatment of new onset T1DM with ATG is therefore expected to alter the behavior of the T cells to halt their attack, and also reduce T cell numbers, so that new T cells that grow in their place will learn to accept the beta cells, rather than attacking them. Following an initial screening appointment, eligible participants will be randomly assigned to one of two groups: the Experimental Group will receive the study treatment while the Control Group that will receive placebo. Each participant has a 2 in 3 chance of being assigned to the treatment group, and a 1 in 3 chance of being assigned to the placebo. The START trial is a blinded study, so neither participants nor study physicians will know to which group an individual has been assigned. All participants will receive intensive diabetes management. Participants in both groups will be admitted to the hospital for 5-8 days to receive infusions of either the study drug or placebo. The duration of the study is 2 years. Participants will have 8 follow-up appointments in the first year and 4 visits in the second year. Most of these visits will last 1- 2 hours. A review of interval health, a physical exam, an assessment of diabetes control including recent 5 day insulin use and blood sugar (e.g., glucose) testing, and blood collection for laboratory testing will occur at each visit. Four of the visits will last about 5 hours, during which participants will undergo mixed-meal tolerance testing (MMTT). This involves drinking a special drink, similar to a milkshake, and having blood specimens taken over a 4-hour period. Subjects will be reimbursed for travel and parking expenses, and will receive compensation for their participation in the longer mixed meal tolerance test visits.