What are possible complications of general anesthetic for an operation if u are a diabetic and a smoker?

Several. Patients with diabetes have a risk of blood sugar abnormalities, increased risk of blood pressure changes, and aspiration of gastric contents if the condition is long standing. Diabetics are also at increased risk of heart attacks. Smokers are at risk for bronchospasm under anesthesia (even if you don't have asthma), low oxygen levels, mucus plugs, and other respiratory complications.