What's a difference between fish oil capsules and omega 3-6-9 capsules? which ones should i take as a diabetic?

That depends: Fish oil is usually omega 3. Fish that consume certain algae deposit that in their flesh. This is definitely good for patients with heart disease and for prevention. Omega 6 comes from vegetables as does 9. 9 is good for the heart and glucose levels. Check with your pcp what they prefer. 3 & 9 convey more benefit for your heart and control inflammation. Your pcp should help you choose best.

None: Krill oil and fish oil are the new snake oil, both are high in omega 3 fatty acids which are extremely fragile. Omega 3 fish oils reduce triglycerides by impairing the liver's ablility to make them. However the oxidative stress caused by fish oil actually raises LDL cholesterol. Some day we may use the phrase "this is just more fish /krill oil" or "here comes the fish/krill oil salesman".