Open-Label Study of Dimethyl Fumarate in Adults With Type 1 Diabetes

Non-Randomized, Parallel-Controlled, Single-Center, Open-Label Clinical Trial Evaluating the Efficacy and Safety of Dimethyl Fumarate in Preserving Pancreatic β-Cell Function in Adults With Type 1 Diabetes

This is a non-randomized, parallel-controlled, single-center, open-label clinical trial designed to evaluate the efficacy of dimethyl fumarate in preserving pancreatic beta-cell function in adults with type 1 diabetes, as well as its safety and tolerability in this population.

Eligible participants are adults aged 18 to 65 years who meet the ADA 2024 diagnostic criteria for type 1 diabetes, have at least 2 positive islet autoantibodies, and have residual beta-cell function as evidenced by a random C-peptide level of at least 200 pmol/L. A total of 96 participants are planned for enrollment, including 32 in the dimethyl fumarate treatment group and 64 in the standard-treatment control group.

Participants in the treatment group will receive dimethyl fumarate enteric-coated capsules in addition to standard insulin therapy for type 1 diabetes. Dimethyl fumarate will be initiated at 120 mg twice daily and increased after 7 days to a maintenance dose of 240 mg twice daily. Participants in the control group will receive standard insulin therapy alone. The intervention period will be 24 weeks, followed by 52 weeks of follow-up.

The primary efficacy endpoint is the baseline-adjusted geometric mean area under the serum C-peptide curve during a 2-hour mixed-meal tolerance test at Week 24. Secondary endpoints include measures of beta-cell function at multiple time points, changes in glycated hemoglobin, proportions of participants with good or poor glycemic control, insulin dose requirements, and immunologic markers including lymphocyte subsets, cytokine profiles, and islet autoantibody characteristics. Safety assessments will include the incidence of flushing, gastrointestinal adverse events, allergic reactions, opportunistic infections, liver function abnormalities, lymphopenia, renal abnormalities, hypoglycemia, severe hypoglycemia, ketosis, and ketoacidosis.

The total study duration is 36 months, from January 2026 to December 2028.

Study Overview

• Status: Recruiting
• Conditions: Type 1 Diabetes Mellitus
• Intervention / Treatment: Drug: Dimethyl Fumarate Enteric-coated Capsules; Drug: Insulin

• Study Type: Interventional
• Enrollment (Estimated): 96
• Phase: Phase 2; Phase 3

Contacts and Locations

• Study Contact: Name: Yong Gu; Phone Number: +86 13814084876; Email: yong.gu@njmu.edu.cn

Study Locations

• China
  • Jiangsu
    • Nanjing, Jiangsu, China, 210029
      • Recruiting
      • Jiangsu Provincial Hospital
      • Contact: Yong Gu; Phone Number: 13814084876; Email: yong.gu@njmu.edu.cn

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Willing and able to participate in the study and provide signed informed consent
• Aged 18 to 65 years
• Diagnosed with type 1 diabetes mellitus according to ADA 2024 criteria
• Positive for at least 2 islet autoantibodies among insulin autoantibody (IAA), glutamic acid decarboxylase autoantibody (GADA), insulinoma-associated protein 2 autoantibody (IA-2A), islet cell antibody (ICA), and zinc transporter 8 autoantibody (ZnT8A)
• Random C-peptide level greater than or equal to 200 pmol/L

Note:

- For participants who have used insulin for more than 14 days, a positive IAA result must be accompanied by at least 2 additional positive autoantibodies other than IAA

Exclusion Criteria:

• Pregnant or breastfeeding women, positive urine pregnancy test at screening, or inability to rule out pregnancy in the opinion of the investigator
• Good glycemic control with oral antidiabetic drugs alone
• Participation in other studies involving diabetes treatment or immunomodulation
• Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than 3 times the upper limit of normal
• Renal insufficiency or evidence of kidney damage, including estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m², urinary albumin-to-creatinine ratio (UACR) greater than or equal to 3.4 mg/mmol (repeat confirmation if necessary), or other kidney disease considered unsuitable for enrollment by the investigator
• History of malignancy, uncontrolled immune system disease, or uncontrolled infection
• Alcohol abuse, drug abuse, psychiatric disorder, or other conditions considered unsuitable for participation in a drug trial
• Use of other immunosuppressive agents within 12 weeks before enrollment
• Participation in any other drug trial within 12 weeks before enrollment
• History of multiple drug allergies, allergic diseases, hypersensitivity constitution, or drug dependence
• Any disease or condition that, in the opinion of the investigator, may interfere with study participation or evaluation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dimethyl Fumarate Plus Standard Insulin Therapy; Participants in this arm will receive dimethyl fumarate enteric-coated capsules in addition to standard insulin therapy for type 1 diabetes. Dimethyl fumarate will be initiated at 120 mg twice daily and increased after 7 days to 240 mg twice daily. The intervention period will last 24 weeks, followed by 52 weeks of follow-up.	Drug: Dimethyl Fumarate Enteric-coated Capsules; Dimethyl fumarate enteric-coated capsules, initiated at 120 mg twice daily and increased after 7 days to 240 mg twice daily.; Other Names: DMF; Drug: Insulin; Standard insulin therapy for type 1 diabetes according to routine clinical practice.
Active Comparator: Standard Insulin Therapy; Participants in this arm will receive standard insulin therapy for type 1 diabetes without dimethyl fumarate. Participants will be followed according to the study schedule for 24 weeks of treatment observation and 52 weeks of follow-up.	Drug: Insulin; Standard insulin therapy for type 1 diabetes according to routine clinical practice.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Baseline-Adjusted Geometric Mean Area Under the Serum C-Peptide Curve During a 2-Hour Mixed-Meal Tolerance Test	The primary efficacy endpoint is the baseline-adjusted geometric mean area under the serum C-peptide curve during a 2-hour mixed-meal tolerance test (MMTT).	24 weeks after end of intervention (48 weeks after enrollment)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Baseline-Adjusted Geometric Mean Area Under the Serum C-Peptide Curve During a 2-Hour Mixed-Meal Tolerance Test	Baseline-adjusted geometric mean area under the serum C-peptide curve during a 2-hour mixed-meal tolerance test (MMTT).	End of intervention (24 weeks after enrollment) and 52 weeks after end of intervention (76 weeks after enrollment)
Change From Baseline in Geometric Mean Area Under the Serum C-Peptide Curve During a 2-Hour Mixed-Meal Tolerance Test	Change from baseline in the geometric mean area under the serum C-peptide curve during a 2-hour mixed-meal tolerance test (MMTT).	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Number of Participants Maintaining Positive C-Peptide Response After a 2-Hour Mixed-Meal Tolerance Test	Number of participants maintaining positive C-peptide response at 52 weeks after end of intervention, defined as a peak C-peptide concentration of at least 200 pmol/L after a 2-hour mixed-meal tolerance test (MMTT).	52 weeks after end of intervention (76 weeks after enrollment)
Glycated Hemoglobin (HbA1c)	Glycated hemoglobin (HbA1c) level and change from baseline.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Number of Participants With Poor Glycemic Control	Number of participants with poor glycemic control, defined as HbA1c greater than 9%.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Number of Participants With Good Glycemic Control	Number of participants with good glycemic control, defined as HbA1c less than 6.5%.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Average Exogenous Insulin Dose	Average dose of exogenous insulin during the 7 days prior to each study visit, expressed as IU/kg/day.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in proportion of peripheral blood CD4+ T cells	Measured by flow cytometry and reported as percentage of lymphocytes.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in proportion of peripheral blood B cells	Measured by flow cytometry and reported as percentage of lymphocytes.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in proportion of peripheral blood natural killer cells	Measured by flow cytometry and reported as percentage of lymphocytes.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in proportion of peripheral blood regulatory T cells	Measured by flow cytometry and reported as percentage of lymphocytes.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in serum interleukin-6 concentration	Measured in serum	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in serum tumor necrosis factor-alpha concentration	Measured in serum	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in number of positive islet autoantibodies	Count of positive islet autoantibodies among GADA, IA-2A, ZnT8A, ICA, and IAA, reported as an integer from 0 to 5.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in glutamic acid decarboxylase autoantibody titer	Measured using an assay-specific method and reported in assay-specific units.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Change from baseline in zinc transporter 8 autoantibody titer	Measured using an assay-specific method and reported in assay-specific units.	End of intervention (24 weeks after enrollment), 24 weeks after end of intervention (48 weeks after enrollment), and 52 weeks after end of intervention (76 weeks after enrollment)
Number of participants with composite treatment-related symptomatic adverse reactions	Participants with at least one occurrence of any of the following treatment-related symptomatic adverse reactions during the safety follow-up period: flushing, abdominal pain, diarrhea, nausea, vomiting, pruritus, rash, erythema, or dyspepsia.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)
Number of participants with composite hypersensitivity or opportunistic infection events	Participants with at least one occurrence of any of the following during the safety follow-up period: immediate hypersensitivity reaction, angioedema, or opportunistic infection.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)
Number of participants with composite laboratory safety abnormalities	Participants with at least one occurrence of any of the following during the safety follow-up period: elevated aspartate aminotransferase, elevated total bilirubin, or lymphopenia.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)
Number of participants with composite renal safety events	Participants with at least one occurrence of any of the following during the safety follow-up period: new-onset or worsening albuminuria, increased serum creatinine, or decreased estimated glomerular filtration rate.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)
Number of participants with hypoglycemia	Participants with at least one episode of hypoglycemia during the safety follow-up period.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)
Number of participants with severe hypoglycemia	Participants with at least one episode of severe hypoglycemia during the safety follow-up period.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)
Number of participants with ketosis	Participants with at least one episode of ketosis during the safety follow-up period.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)
Number of participants with diabetic ketoacidosis	Participants with at least one episode of diabetic ketoacidosis during the safety follow-up period.	From first dose to 52 weeks after end of intervention (up to 76 weeks after enrollment)

Collaborators and Investigators

• Sponsor: Nanjing Medical University
• Investigators: Principal Investigator: Yong Gu, Department of Endocrinology, Jiangsu Provincial Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): April 27, 2026
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: April 14, 2026
• First Submitted That Met QC Criteria: April 21, 2026
• First Posted (Actual): April 23, 2026

Study Record Updates

• Last Update Posted (Actual): April 23, 2026
• Last Update Submitted That Met QC Criteria: April 21, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Type 1 Diabetes; Dimethyl Fumarate; Beta-Cell Function
• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Autoimmune Diseases; Immune System Diseases; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Diabetes Mellitus, Type 1; Hormones; Hormones, Hormone Substitutes, and Hormone Antagonists; Peptide Hormones; Peptides; Amino Acids, Peptides, and Proteins; Insulins; Pancreatic Hormones; Proinsulin; Insulin
• Other Study ID Numbers: 2026-SR-107

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Deidentified individual participant data will not be shared due to institutional policies, ethical requirements, participant consent limitations, and data protection considerations.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No