Effects of Different Fish Oil Types on Type 2 Diabetes Risk Factors in High-Risk Adults (END-T2D)

Background and Rationale:

According to the International Diabetes Federation, about 590 million adults worldwide-or 1 in 9 adults-were living with diabetes in 2025, most of whom had type 2 diabetes (T2D). An additional 230 million adults (about 4 in 10) are unaware that they have diabetes and therefore remain undiagnosed. Diabetes substantially increases the risk of illness and death and has an impact comparable to aging approximately 15 years, making it a leading cause of disability and mortality worldwide.

Type 2 diabetes develops gradually as multiple risk factors accumulate over time, including unhealthy lifestyle habits and aging. These factors reduce the body's ability to produce insulin and/or respond effectively to insulin, a hormone that regulates blood sugar levels. As a result, blood sugar levels progressively rise and may eventually lead to a diagnosis of T2D.

Importantly, type 2 diabetes is preventable.

In people with T2D, elevated blood levels of apolipoprotein B (apoB) increase the risk of cardiovascular disease (apoB is a measure of the number of particles that carry "bad" cholesterol known as low density lipoproteins (LDL)). Traditionally, high apoB levels were considered a consequence of T2D. However, research from the principal investigator's laboratory has shown that high apoB levels may also contribute to the development of T2D.

This appears to occur because LDL particles can promote inflammation and impair the normal function of fat tissue. Poorly functioning fat tissue is associated with multiple metabolic abnormalities that increase the risk of both T2D and cardiovascular disease. Large population based studies confirmed that elevated blood apoB levels can predict the development of T2D many years before diagnosis.

Recent findings from the research team also indicate that 12 week supplementation with marine derived omega 3 fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), can improve several risk factors for T2D, particularly in individuals with higher blood apoB levels. However, these data suggest that EPA and DHA may not provide identical benefits in reducing these risk factors.

Study Objective:

The overall aim of this study is to compare the effects of EPA versus DHA on major risk factors for T2D in adults with overweight or obesity and elevated blood apoB levels.

Study Design and Procedures:

After eligibility is confirmed, participants will visit the research institute (IRCM) for two baseline visits scheduled one week apart. During these visits, investigators will used specialized metabolic testing to:

1. Assess how participants' bodies process glucose and produce insulin using blood samples, and
2. Examine how participants' fat tissue responds to their own LDL using a small fat tissue biopsy.

Participants will then be randomly assigned to follow one of three interventions for 12 weeks: EPA, DHA or corn oil (placebo). At the end of the 12 week intervention, participants will return to the research institute to undergo the same assessments performed at baseline.

Data Analysis:

At the conclusion of the study, results from participants in each intervention group (EPA, DHA, and placebo) will be averaged and compared. This will allow researchers to determine the effects of EPA and DHA on key risk factors for T2D and to evaluate whether one omega 3 fatty acid is more effective than the other.