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Avoiding Nighttime Lows

Nighttime hypoglycemia can be the result of a number of factors in people with diabetes, according to Howard Wolpert, M.D., Director of the Joslin Diabetes Center Insulin Pump Program.  It’s important to learn what causes low blood glucose reactions, so you can figure out how to prevent them from happening.

Causes of Nighttime Hypoglycemia

Having an active day or exercising close to bedtime with diabetes can decrease your blood glucose and cause a hypoglycemic reaction during sleep.  Consuming alcohol in the evening can also put you at risk for a lower blood glucose level.  This is a result of your liver clearing the alcohol from your blood, instead of producing glucose.

In addition, some people forget that their bolus/fast-acting insulin lasts for up to five to six hours. If you have a late dinner and go to sleep a couple hours later, your blood glucose may be normal before going to bed.  However, since the insulin you took for dinner is still acting in your body, your blood glucose could drop during the night.

Signs of Nighttime Hypoglycemia

Signs that you’ve experienced nighttime hypoglycemia can include:

  • Sweating: waking up with damp clothes/sheets
  • Waking up with a headache
  • Having nightmares

You may also wake up with a higher blood glucose reading, which is a result of your body rebounding from the overnight low.  Experiencing a fast heartbeat and anxiety before bed may be an indication of approaching hypoglycemia.

Ways to Avoid Nighttime Hypoglycemia

Your target blood glucose reading before bed should be at least 140 mg/dl, Wolpert says.  Before you go to bed, consider all of the causes of nighttime hypoglycemia, and if you think you’re at risk, have a snack before heading to sleep.  If you use an insulin pump, one option is to reduce your basal rate.

If you find yourself experiencing nighttime lows often, you may want to consider purchasing a continuous glucose monitoring device (CGM), which alerts you when you’re experiencing a low blood glucose or a high, suggests Wolpert.  It may also be a good idea to speak with your doctor about adjusting your insulin regimen.

To make an appointment with a Joslin physician, please call (617) 732-2400.

To register and learn about Joslin's Blood Glucose Awareness Training workshop, click here.

Blood Sugar Monitoring Owner's Manual offers all the guidance one needs to understand why blood glucose monitoring is important, when and how to check blood glucose, setting target goals, potential “road blocks” and how to get around them.

Click here, to purchase this book from the Joslin Store.

Page last updated: November 07, 2019