As a T2 your blood glucose is high because all the places you can put the surplus energy that you are taking in are now full. Glycogen (liver and muscle) gets full first, you can store only about 1500 to 2000 Calories there. Then comes the adipose fat (under the skin) you can store huge amounts of energy here, but how much varies from person to person, by genetics and by age it's like long term battery storage of energy 50 lbs of fat is about 175,000 Calories. Eventually if you keep overconsuming calories this compartment gets too full (existing fat cells can take no more energy, nor can your body make new fat cells, the amount of adipose fat at which this happens is influenced greatly by your genetics and age). Once the adipose compartment is full and you are still overconsuming, the body is still pumping out insulin like crazy, so new fat stores within the belly are created, around the internal organs. When that compartment is full if you continue to overconsume the body packs the excess energy away in ectopic fat in the liver, in the pancreas, and intra muscular fat. Eventually this compartment becomes full if you continue overconsuming. Now the excess energy you consume, whether carbohydrates, fat or protein will stay in your blood stream, high blood sugar, high triglycerides and high cholesterol. Your body will work like crazy to excrete what it can (hence the trips to the toilet to urinate and get rid of glucose). Insulin cannot pack this stuff away anywhere. It's all full. Drugs like metformin make you fat cells more sensitive to your insulin and allow you to cram some excess energy away in you fat cells again. But if you keep overconsuming the same cycle means you pack away more fat in all compartments, and they are too full. Next step, insulin injections, and you've guessed it .. same cycle if you keep overconsuming.
Exercise allows your muscles to use some of the energy in your blood stream even if, walking after meals will reduce the sugar spike. High intensity exercise will (e.g. lots of shuttle sprints, boxing, HIIT etc.) cause creation of glucose by the liver as the anticipation is that you need more for this potentially flight or flight event as your physiology perceives it. Any of that liver dump you don't use will eventually get either excreted (assuming your fat stores are full to capacity still) or reformed to glycogen in the liver and muscles. That's the short term. Longer term, regular exercise in combination with a reduction in you calorific intake will start to reduce your fat stores, eating less carbohydrates will also free up space in your liver and muscle glycogen compartments, building more muscle will also increase the size of capacity the glycogen compartment. Losing fat will increase the size of available storage capacity in the fat compartment.
Regular exercise helps a lot, but diet is by far most important. If your are T2 and you want to improve your long term average blood sugar levels, you have to eat less energy than you're expending to perform your daily activities, fuel the metabolic process required to stay alive, grow and repair. So that your body is forced to use its fat stores to fuel your energy requirements. As a T2 going low carb is a good idea, don't go crazy on the "healthy fats" they're energy dense and if you over consume you wont lose weight. Easiest way I found is to eat lots of Protein as it is very filling, avoid sugars and starchy vegetables, limit fat intake. Your body can make all the glucose you need even if you eat no carbs. High quality protein (i.e. all essential amino acids) is a must, you can't make protein from carbs or fat, you have to consume it for growth and repair. If you get all your protein from whole foods like eggs, meat, dairy etc. you'll get enough of the essential fats that you need (like the healthy) omega fats, don't feel the need to add loads of extra fat to your food like some keto diet people do. Make those exercise and diet changes and over time things get better. If you are taking meds for your T2, check with your doctor about changes to to your prescription as you don't want hypos. If you start to exercise, eat less carbs and still take the same amount of metformin or insulin as you did before you'll get into trouble with low blood glucose levels. But in summary with lower fat and more muscle the body can deal with the increased blood glucose after a meal and put it into storage. As long as you do not overconsume this stored fat will be released from time to time to fuel your body between meals.
That a high level overview of what diet and exercise can do for a T2, remember you can't out exercise a bad diet. There's more benefits than just reduced blood glucose though with exercise and a good diet, but that's a long long list. I'm only mentioning macronutrients here for brevity's sake, but keep the diet varied so you get enough micronutrients too (vitamins, minerals etc.).
It's a lifestyle change .. once you make the change and see/feel the benefits you'll be glad.
