Yumin,
While the usual effect of exercise is to reduce blood sugar, it can have the opposite effect. Strenuous exercise causes an increase in adrenalin. Which, in turn, causes your liver and muscles to release stored glycogen. So your blood sugar goes up.
Cheers,
Mark
Hello again Yumin
(I just posted a comment to your question about high blood glucose in the morning, too).
I'm not a physician, so please do check with your doctor about the information you read here & other places.
There is a complex balancing needed for us to maintain blood sugar levels within the range our doctors have recommended. In general, exercise & insulin bring our sugar levels down. Whether it's insulin that your body is producing or insulin that others take in injections or by pump, insulin lowers blood sugar. Exercise normally does, too.
Food raises blood sugar -- particularly food wth carbohydrates.
In general, fresh fruit is an EXCELLENT choice for diabetics as part of our overall meal plan. Each of us must learn how to eat a balanced diet with lots of variety. One day, we might eat a sweet juicy peach for our snack; another day we might have a banana instead; yet another day, we might have some milk & crackers.
In general, exercise is also EXCELLENT and important for diabetics.
Perhaps your doctor is using the next few weeks until your next appointment -- for you to collect data about your blood sugars without any medication. Once s/he sees the ranges, s/he might then suggest oral medication (to help your body produce/use its own insulin more effectively) or insulin. If you are overweight, it is important for you to talk to the doctor about an exercise program & way of eating that will help you lose weight. Many folks with Type 2 diabetes (which I assume you have since Type 1 diabetics MUST take insulin to live) will find their symptoms go away when they get closer to a healthy normal body weight. Not all Type 2s are overweight, but many are.
Amputation is a terrible outcome that most of us plan NOT to experience. Occasional high blood sugar doesn't cause the need for an amputation, but weeks, months & years of hihg blood sugars destroys our circulation system and damages eyes, kidneys, digestive system, nervous system, and can lead to the need for amputations. From what I have seen, it seems that the body protects the "trunk" and major organs & limbs as long as possible even if it means sacrificing toes or feet.
Amputation is NOT something you should plan for. It is something you should plan to AVOID by learning all you can about this disease and how to take good care of yourself.
I have had diabetes for over 35 years and many here have had it even longer. One key to success is learning, and learning some more (like coming to places like this), getting medical care from a diabetic specialist (NOT a general doctor, but an endocrinologist or diabetologist), and finally finding support & motivation to do what it takes to be healthy.
Ping-pong & peaches can easily be part of your life, so enjoy them!!