But in studies where saturated fat intake remained constant while fish oil increased, LDL levels either didn't change or increased. Taking fish oil capsules doesn't seem to impair glucose tolerance in nondiabetic coronary bypass patients. The effect of fish oil on diabetics is harder to determine. Early studies showed a deterioration in glucose tolerance in people taking fish oil. Later studies have suggested that fish oil may have some benefits for people with diabetes.
More research is needed before anything definitive can be said.
On blood pressure Fish oil doesn't affect the blood pressure of people whose blood pressure is normal. It does appear to lower blood pressure in people who have high blood pressure and hypercholesterolemia . But the reduction isn't much, and the effect may not last. While this effect can be useful in some cases, it may also be harmful. It's a potential risk when large amounts of fish oil are consumed.