There are three main types of diabetes: Type 1 diabetes: is caused by an autoimmune reaction (the body attacks itself by mistake) that stops your body from making insulin. It’s usually diagnosed in children, teens, and young adults. If you have type 1 diabetes you’ll need to take insulin every day to survive. Type 2 diabetes: your body doesn’t use insulin well and is unable to keep blood sugar at normal levels. Most people with diabetes .It develops over many years and is usually diagnosed in adults (though increasingly in children, teens, and young adults). You may not notice any symptoms, so it’s important to get your blood sugar tested if you’re at risk. Type 2 diabetes can be prevented or delayed with healthy lifestyle changes, such as losing weight if you’re overweight, healthy eating, and getting regular physical activity.