Hi
It would depend when you had taken the readings. The best time is in the morning before you eat or drink. Then 2 hours after food to see how your body coped with it.
Some medication can alter blood sugar levels
With heart disease and your medication we are going to be reluctant to give you dietary advice but if you read around the forum you will see that carbohydrates , in simple terms, turn into sugar in the blood and raise your levels.
Please ask for professional advice but consider trying to lose weight, exercise more if you are allowed to and look for for carbohydrates in the form of sugar, potatoes, rice, pasta, cereal fruit juices.
Ask your pharmacist if any other medications you take can effect blood sugar.
ask for a longer appointment with your GP or a different one, and go over your concerns in more detail. Keep a track of what you eat and when you test.
Let us know how you get on
Cara