I am a teenager that takes Ritalin. I was wanting to know if it causes any kind of diabetes?

I would assume you were prescribed this medication by a doctor whether that is a GP, pediatrician, or psychiatrist all know what the side effects of the medication are and if they are going to be bad for you. In some cases medication can have a contraindication but the positive aspects override the negative aspects and closer monitoring is given. If you have questions you should run them by the prescribing doctor.

....."Blood glucose changes: Individuals with diabetes mellitus or borderline glucose tolerance could potentially see a rise in blood sugar. On the other hand, if the stimulant cuts one’s appetite, one may use less insulin. Individuals with diabetes can often take stimulants, but they may need closer monitoring of their diabetic control."

I scanned three or four sites and saw nothing that said diabetes was a side effect. However, you should talk to your dr. Good luck and happy new year!