Low-Dose Anti-Thymocyte Globulin Preserves C-Peptide, Reduces HbA1c, and Increases Regulatory to Conventional T-Cell Ratios in New-Onset Type 1 Diabetes: Two-Year Clinical Trial Data

Diabetes. 2019 Jun;68(6):1267-1276. doi: 10.2337/db19-0057. Epub 2019 Apr 9.


A three-arm, randomized, double-masked, placebo-controlled phase 2b trial performed by the Type 1 Diabetes TrialNet Study Group previously demonstrated that low-dose anti-thymocyte globulin (ATG) (2.5 mg/kg) preserved β-cell function and reduced HbA1c for 1 year in new-onset type 1 diabetes. Subjects (N = 89) were randomized to 1) ATG and pegylated granulocyte colony-stimulating factor (GCSF), 2) ATG alone, or 3) placebo. Herein, we report 2-year area under the curve (AUC) C-peptide and HbA1c, prespecified secondary end points, and potential immunologic correlates. The 2-year mean mixed-meal tolerance test-stimulated AUC C-peptide, analyzed by ANCOVA adjusting for baseline C-peptide, age, and sex (n = 82) with significance defined as one-sided P < 0.025, was significantly higher in subjects treated with ATG versus placebo (P = 0.00005) but not ATG/GCSF versus placebo (P = 0.032). HbA1c was significantly reduced at 2 years in subjects treated with ATG (P = 0.011) and ATG/GCSF (P = 0.022) versus placebo. Flow cytometry analyses demonstrated reduced circulating CD4:CD8 ratio, increased regulatory T-cell:conventional CD4 T-cell ratios, and increased PD-1+CD4+ T cells following low-dose ATG and ATG/GCSF. Low-dose ATG partially preserved β-cell function and reduced HbA1c 2 years after therapy in new-onset type 1 diabetes. Future studies should determine whether low-dose ATG might prevent or delay the onset of type 1 diabetes.

Trial registration: ClinicalTrials.gov NCT02215200.

Publication types

  • Clinical Trial, Phase II
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Antilymphocyte Serum / therapeutic use*
  • C-Peptide / metabolism
  • CD4-CD8 Ratio
  • Child
  • Diabetes Mellitus, Type 1 / drug therapy*
  • Diabetes Mellitus, Type 1 / immunology
  • Diabetes Mellitus, Type 1 / metabolism
  • Double-Blind Method
  • Female
  • Flow Cytometry
  • Glycated Hemoglobin A / metabolism
  • Granulocyte Colony-Stimulating Factor / therapeutic use
  • Humans
  • Immunologic Factors / therapeutic use*
  • Male
  • T-Lymphocytes, Regulatory / immunology
  • Young Adult


  • Antilymphocyte Serum
  • C-Peptide
  • Glycated Hemoglobin A
  • Immunologic Factors
  • hemoglobin A1c protein, human
  • Granulocyte Colony-Stimulating Factor

Associated data

  • ClinicalTrials.gov/NCT02215200