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  • With Mayo Clinic diabetes educators

    Nancy Klobassa, R.N., and Peggy Moreland, R.N.

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  • June 23, 2009

    Blog: Driving with diabetes

    By Nancy Klobassa, R.N., and Peggy Moreland, R.N.

4 comments posted

Those of you who have diabetes understand the importance of maintaining blood sugar (glucose) levels in your goal range. High or low blood sugar levels can result in sleepiness, confusion, blurred vision, or loss of consciousness.

Too high or too low blood sugar levels are dangerous when you're behind the wheel of a car. Monitoring your blood sugar is important if you're the driver. Stress, time changes, and changes in your eating and sleeping schedule can affect your blood sugar level, so it's best to test more frequently when driving with diabetes.

Hypoglycemia is an abnormally low blood sugar level typically less than 70 milligrams per deciliter or 3.9 millimoles per liter. Early symptoms of low glucose include shakiness, dizziness, hunger, headache, lightheadedness, moodiness, pallor, and confusion. As blood glucose levels continue to drop, loss of consciousness and seizures may result. Some people aren't aware that their blood glucose is dropping. This is a condition known as hypoglycemia unawareness.

Hyperglycemia is an abnormally high blood sugar level of 180 mg/dL (10 mmol/L) or greater. Symptoms of hyperglycemia that you may notice while driving include blurred vision, fatigue, hunger, excessive thirst, and frequent urination. Symptoms and effects of hyperglycemia may not be noticeable until blood sugars are above 250 mg/dL (13.9 mmol/L).

If your blood sugar is too low or too high you may not be able to focus on driving or control your car.

Some tips for driving with diabetes:

  • Always test your blood sugar before driving.
  • If the value is below 100 mg/dL (5.6 mmol/L) don't drive. Eat and retest and drive when blood sugar is above 100 mg/dL (5.6 mmol/L).
  • Follow rule of 15 — treat blood sugar below 70 mg/dL (3.9 mmol/L) with 15 grams of fast-acting carbohydrate — and retest in 15 minutes. Test and retreat every 15 minutes until blood glucose is up in goal range.
  • Always carry a source of carbohydrate in your car.
  • Test blood sugar every two hours when driving long distances.
  • Don't drive with impaired vision.
  • Wear a diabetes medical ID.
  • Insulin and some medications can cause low blood sugar. Test your blood sugar before you drive and don't drive if your blood sugar is too low. Check with your health care team as to how often you should check during the drive.
  • Don't miss or delay a snack (depends on your diabetes medication program).
  • It's never OK to drive with a low blood sugar. Stop the car if you experience symptoms of hypoglycemia. Check your blood sugar. Treat with fast-acting sugar tablets, juice, regular soda, or hard candy. Wait 15 minutes. Test and treat again as needed. Do not drive until your blood sugar level has reached your blood glucose range. You should eat a more substantial meal containing protein as soon as possible.

Supplies to take with you:

  • Glucose meter
  • Snacks (in case meals are delayed), a fast-acting sugar such as glucose tablets, juice, regular soda, or hard candy.

It's always good to consider how well you're managing your diabetes. Are you on track with counting carbohydrates and taking your medications at the right times? Foods and the timing of foods change as does your activity level on trips. Be aware that insulin doses may change according to what you're eating or doing.

Any additional tips for driving with diabetes are welcome!

- Peggy

4 comments posted

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  • July 28, 2009 4:26 p.m.

    THIS WILL SOUND JUDGEMENTAL, BUT IT ISN'T. IT IS AN OBSERVATION: "YOU HAVE A CHOICE!" - NOTE: I am speaking w/ only one eye working, nasty periph polyneuropathy, heart disease etc. In other words, I didn't "walk the walk." - So now I do and I monitor, monitor, monitor! I watch what I eat ruthles-sly (a real pain in the neck), I do everything right, NOW. So I can still drive, still do a lot of things I hear other people living w/ diabetes say they can't. It's a tradeoff. You do the tough stuff (mostly at home by the way) by disciplining yourself, and you end up having a somewhat normal life. Or you don't, and you are then become quite limited in your abilities and lifestyle. Take your pick! Either one is OK as it is Y-O-U-R life, Y-O-U-R choice! No one else (non diabetic) really cares what you do. (BUT I DO, AS I AM YOU!)

    - CHIP

  • June 25, 2009 10:03 a.m.

    I am not aware of sugar dropping untill it dropes to almost 50 then get a shakey and I have visual problem loosing focus. That does not give me much warning so I have reduced my driving and I do not travel on highway with high traffic with not easily being able to park it scares me! Always have glucose tabs in my pocket. I am considering selling my car as I am worried about the risk. I think anyone that has this problem should seriously consider stopping driving for your safty and for possability of harming others.

    - Ann Carroll

  • June 25, 2009 1:50 a.m.

    Just read the comments/questions on driving with diabetes. A little less that 2 years ago, I was going to see a friend (less than 1 mile away). I pulled out of my complex and then turned on a road that led me to a very busy road. To this day I could not tell you why I was not hit. I passed out right after I pulled out from my complex, obviously hit some bricks and blew a tire; then ended up in the middle of this busy street and woke of a saw one car sitting right at my car door. This is a normally extremely busy street. The woman never got out to check on me. I turned around and back to my place and sat in from of my neighbors place and blew my horn till he came out. I could not remember anything. All I know is someone up their was taking care of me. I promised at that moment I would never drive again. So please think carefully about driving. Thank you again Nancy and Peggy

    - Claire Bebbington

  • June 23, 2009 8:33 p.m.

    I like the Rule of 15--haven't really heard of that before.

    - Marcella

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