How can Buddhism help me to get rid of a suffering due to a disease?

I came to know about Buddhism very late in my life. It is the time for me to relearn the fundamentals of life. But I struggle with everyday activity. I lack energy. In fact I have a diabetes. My past Karma has been bad enough to get me a disease. My question is: How can Buddhism help me get rid of this disease? If I fix my Karma then will the suffering due to the disease will disappear ? If yes, how can I repent and to whom ?