We can't have blood transfusions, but a Witness friend of mine is a diabetic and injects himself four times a day with insulin. What's the difference?
Diabetics and insulin
Insulin is a hormone made from the pancreas. It isn't a blood product that I am aware of. Of course EVERYTHING in the human body is affected by and fed by the blood cells. . .but that is beyond their purview:)
Injectable insulin is not a human by-product. Some is made from pork (that's old school) and I believe most is actually chemical concoctions. -Potential