This trial has undergone a prespecified interim analysis which determined that this treatment provides no statistically significant delay in the onset of abnormal glucose tolerance or Type 1 Diabetes.

The study is a 2-arm, double blinded, multicenter, 2:1 randomized, placebo controlled clinical trial. Subjects will receive hydroxychloroquine or placebo and close monitoring for progression of T1D.

This study is testing a medication, called hydroxychloroquine (HCQ) to assess safety and effectiveness to prevent individuals at risk of type 1 diabetes (T1D) from progressing to type 1 diabetes.

HCQ is approved by the U.S. Food and Drug Administration as a treatment for malaria, lupus, and rheumatoid arthritis. HCQ has been used extensively for treatment of autoimmune disease in adults, children, and during pregnancy. This medication has not previously been studied as a treatment to prevent T1D.

The goal of this study is to learn if HCQ can help prevent or delay progression from normal glucose tolerance (Stage 1) to abnormal glucose tolerance (Stage 2) or type 1 diabetes (Stage 3).

The study involves 5 visits in the first 6 months, then 1 visit every 6 months for the remainder of the study.

Inclusion Criteria:

1. Participant in TrialNet Pathway to Prevention Study (TN01)
2. Age 3 years or greater at the time of randomization
3. Willing to provide informed consent
4. Normal glucose tolerance by OGTT within 7 weeks (no more than 52 days) of baseline
5. Two or more diabetes-related autoantibodies present on two separate samples
6. Weight of 12 kg or greater at screening
7. If a female participant with reproductive potential, willing to avoid pregnancy and undergo pregnancy testing prior to randomization and at each study visit
8. Anticipated ability to swallow study medication.

Exclusion Criteria:

1. Abnormal Glucose Tolerance or Diabetes
2. History of treatment with insulin or other diabetes therapies
3. Ongoing use of medications known to influence glucose tolerance
4. Ongoing or anticipated future use of medications known to have untoward interactions with hydroxychloroquine
5. Known hypersensitivity to 4-aminoquinoline compounds
6. G6PD deficiency
7. History of retinopathy
8. Have an active infection at time of randomization
9. Have serologic evidence of current or past HIV, Hepatitis B (positive for Hepatitis B core antibody or surface antigen), or Hepatitis C infection
10. Deemed unlikely or unable to comply with the protocol or have any complicating medical issues, including prolonged QT interval, a disease previously or likely in the future to require immunosuppression, or abnormal clinical laboratory results that interfere with study conduct or cause increased risk.
11. Deemed unlikely or unable to comply with the protocol or have any complicating medical issues, including prolonged QT interval, a disease previously or likely in the future to require immunosuppression, or abnormal clinical laboratory results that interfere with study conduct or cause increased risk.
12. Be pregnant or breastfeeding.

Active drug and placebo will be identical in appearance and packaging