Most Common Causes of Low Blood Sugar


There are several reasons why low blood sugar can occur:

  • Taking too much insulin or other blood glucose-lowering medicine.
  • Not eating enough carbohydrate or delaying or skipping a meal. Common foods that contain carbohydrate are: fruits, vegetables, breads, bagels, muffins, crackers, pasta, starchy vegetables, grains, milk, yogurt, sugary foods, and sweets.
  • Being more physically active than usual without taking less medicine or eating more carbohydrate.
  • Drinking alcohol. Alcohol can make it hard for your body to keep your blood sugar level up, especially if you are taking insulin or a blood glucose medicine that may cause a low. Alcohol can affect your blood sugar level while you're drinking and for several hours afterward.
  • Attempting to maintain extremely tight blood sugar control within a narrower range than recommended.
  • Mixing up your rapid- and long-acting insulin (by accident).
  • Weight loss. As you lose weight your body can become more sensitive to the insulin you're making and/or taking.

It's not always easy to identify why your blood sugar went too low. What's important is correcting it right away. Later, take some time to reflect on what may have caused it. This may help you keep low blood sugar from happening often. And don't forget, always be prepared!


By Hope Warshaw, MMSC, RD, CDE, diabetes educator, consultant, and Coordinator of the Perrigo Diabetes Care advisory board; and Riva Greenberg, diabetes patient-expert, author, speaker, and Huffington Post columnist contributed to this article.

Last Modified Date: July 09, 2014

All content on is created and reviewed in compliance with our editorial policy.

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