Hello Jen, welcome to our support group! It depends on what kind of diabetes you have. I am type 1 and I became very ill when I was 5 years old and the illness caused my pancreas to stop producing insulin. I was very skinny and underweight when diagnosed in 1945. Anything that damages your pancreas can cause type 1 diabetes. Type 2 diabetes occurs when the body is still producing insulin but is not able to utilize that insulin effectively. That is called insulin resistance. Being overweight can cause the body to have that resistance but there are other causes of resistance like the side effects of some medications. Most overweight people do not become diabetics. There is much more to it than what I have said. I suggest that you use a search engine like Google and research this topic. Google "Causes of diabetes" and see what you find.
Richard
Richard