Should you take your insulin or antidiabetic medication before going for your fasting blood tests?
No. You should never take your insulin or antidiabetic medication prior to having a fasting blood test.
The first reason is because the injected insulin will lower your glycemia and you could find yourself in a state of hypoglycemia. The second reason is that your test results will be skewed, their interpretation inaccurate, making your glycemic control difficult because the insulin will have already begun to act when your blood test was done.
You should book your appointment for as early in the morning as possible. Once your blood test is done, check your blood glucose (sugar) levels and give yourself your injection, or take your antidiabetic medication, and then eat breakfast. You should eat within minutes of taking insulin. If you don’t, you risk becoming hypoglycemic.