Could you tell me what's the best way to stabilize the blood sugar level?

That depends: If you have diabetes, work w/your doctor and your diabetes team to help control your sugar. If you don't have diabetes, then blood sugar should be stable by itself, as people don't develop spontaneous low sugar, no matter what you've read. They do, however, get above normal sugars as they age, particularly if at all overweight with a positive family history.