In order to obtain and maintain a commercial driver's license, you must undergo a Department of Transportation medical exam. If you pass with no problems, you will have to renew the medical card every two years. If you have high blood pressure and/or diabetes, you may have to have more frequent physical exams in order to remain qualified for your license.

High Blood Pressure

Having high blood pressure does not disqualify you from obtaining a CDL. However, having uncontrolled high blood pressure does. If your blood pressure is less than 140/90, and you do not suffer from kidney disease or have diabetes, you will be given a normal health card. Having kidney disease or diabetes means you need to keep it less than 130/80. If your blood pressure is between the normal range and 159/99 you will need to see your doctor and find a way to bring it down to normal within one year. If your blood pressure is as high as 179/109 you will have three months to initially bring it down to within the normal range. If you succeed, you will need to have an exam annually after that. Anything above that will disqualify you until you can get it down to normal. Once normal, you will need to have an exam every six months.

Diabetes

Like blood pressure issues, having diabetes does not mean you cannot have a CDL. However, if you are insulin dependent you will require a special waiver to be given the license. The DOT medical examiner will need to have access to your medical records, specifically the results from your HBA1C tests. Your current result must be lower than 10 percent to receive a one year medical card. If your results are between 10 and 12 percent, you will be given a three month card and the chance to bring it down to under 10 percent. In addition to these results, you must not have had a hypoglycemic episode that resulted in a seizure, loss of consciousness or the need for help in the last year, or two episodes in the past five years. You cannot be suffering with any of the complications that are caused by diabetes, like macular degeneration of the retina, peripheral neuropathy, kidney failure or congestive heart failure.

Uncontrolled high blood pressure or diabetes can result in you losing the ability to drive safely. You may become disoriented or pass out. When driving commercially, you are most likely either driving with many passengers or a large load. The risk to other people is too great if you do not have your conditions under control. Follow your primary care physician's directions, and you should be able to keep everything at the levels the DOT medical examiner will be happy with and allow you to keep your license.