If you smoke and have been diagnosed with diabetes, your doctor will recommend that you quit because smoking makes problems caused by diabetes worse. People with diabetes can experience blood flow problems in the legs and feet, which can sometimes lead to amputation. Smoking can decrease blood flow even more. Smoking can also worsen sexual impotence in men, cause high levels of LDL cholesterol (the bad type of cholesterol), and can raise the risk of heart attack and stroke. If you have diabetes and you smoke, you need to quit.