One of the things to understand about COVID-19 is that we are still learning, and we continue to learn. One thing we do know is that people with diabetes seem to develop more severe COVID disease. It's not that people with diabetes are more prone to COVID, but if they develop COVID, the disease is much more severe and seems to progress quicker. That seems to happen both with type 2 and type 1 diabetes, and both seem to be prone to more severe disease though Type 1 patients may do better because they're younger.
Type one diabetes is a disorder in which most of the insulin producing cells in the body are destroyed by an immune process. Type 2 diabetes involves an interaction between genetic predisposition and the environment, so the environment in the sense that increased food intake, decreased physical activity, increased weight, interact with their family history which provides the genes.
In people with diabetes there is more inflammation in the body. And so, with COVID, that inflammatory state gets worse much more quickly, so that could be one reason. The second reason is people with diabetes may be more prone to having problems with their circulation, they may already have had a bypass or a stroke or low blood flow to the legs or something like that. And then this was since that because there's an addition circulatory problem on top of a background of circulatory issues. Blood flow because of clotting problems could be exaggerated by COVID. So, within each one of these bigger reasons there may be smaller reasons nested.
So, you can see people with diabetes were helped; adverse effects, really speaking, seem to be very minimal in the sense of having maybe mild fever and headache, muscle aching, and joint discomfort. But that seems to last less than 48 hours. So yes, people with diabetes should get the vaccine.