Do omega-3 fatty acid supplements increase the risk of diabetes?

Omega-3 Fatty Acid Supplements and Diabetes Risk

Based on the available evidence, omega-3 fatty acid supplements do not increase the risk of diabetes, but they may worsen glycemic control in some patients with existing diabetes, particularly at higher doses. 1

Effects on Glycemic Control

The relationship between omega-3 supplements and diabetes shows some important nuances:

In People Without Diabetes:

• Current evidence does not indicate that omega-3 supplements increase the risk of developing diabetes in the general population
• Guidelines focus more on cardiovascular effects rather than diabetes risk

In People With Existing Diabetes:

• Several studies have shown potential adverse effects on glycemic control:

  • Fasting glucose levels increased by 22% in some studies 2
  • Meal-stimulated glucose increased by 35% in certain populations 3
  • Basal hepatic glucose output increased without changes in glucose disposal rates 2

• The effect appears to be:

  • Dose-dependent (more pronounced with higher doses)
  • Reversible upon discontinuation of supplements
  • More significant in overweight individuals (correlation with percentage of ideal body weight) 3

Mechanism of Action

The potential mechanisms for worsened glycemic control include:

• Increased hepatic glucose output 2
• Impaired insulin secretion in response to meals or glucagon stimulation 2
• No significant change in insulin sensitivity or glucose disposal rates

Clinical Recommendations

The American Diabetes Association (ADA) provides clear guidance:

1. For cardiovascular prevention: "Evidence does not support recommending omega-3 (EPA and DHA) supplements for people with diabetes for the prevention or treatment of cardiovascular events." 1

2. For dietary intake: "As recommended for the general public, an increase in foods containing long-chain omega-3 fatty acids (EPA and DHA) (from fatty fish) and omega-3 linolenic acid (ALA) is recommended for individuals with diabetes because of their beneficial effects on lipoproteins." 1

3. Recommended food sources: "The recommendation for the general public to eat fish (particularly fatty fish) at least two times (two servings) per week is also appropriate for people with diabetes." 1

Important Considerations

• Lipid effects: Omega-3 supplements consistently reduce triglycerides (by 42-56%) and VLDL cholesterol, which may be beneficial in diabetes management 3

• Dose matters: Higher doses (8g/day) show more pronounced effects on both glucose elevation and triglyceride reduction 3

• Individual variation: The glucose-elevating effect correlates with body weight, suggesting overweight individuals may be more susceptible 3

• Recent research: A 2023 meta-analysis suggests omega-3 supplementation may reduce cardiovascular disease risk in patients with diabetes, with EPA alone showing more benefit than EPA+DHA combinations 4, though this contradicts earlier ADA guidance

Clinical Monitoring

For patients with diabetes who choose to take omega-3 supplements:

• Monitor fasting glucose levels more frequently after initiating supplements
• Consider lower doses (less than 8g/day) to minimize glucose elevation
• Be particularly cautious in overweight patients with type 2 diabetes
• Consider discontinuing if significant deterioration in glycemic control occurs

Bottom Line

While omega-3 supplements do not appear to increase the risk of developing diabetes, they should be used cautiously in patients with existing diabetes due to potential adverse effects on glycemic control. The ADA recommends obtaining omega-3 fatty acids from food sources (fatty fish twice weekly) rather than supplements for people with diabetes.