Suggest Treatment For Rapid Heartbeat With Low Magnesium Level

rapid heart beats filling faint low magnesium, very hyper person diabetes in family, grandmother died with massive heart attack at age 69 , but she smoked, I never smoked dont drink no other health problems was hospitalized for same thing a year ago. doctors said last time,low electrilites, please help me understand what is happening to me , Im 50 years old