Hypoglycemia (Low Blood Glucose): Diabetes Head to Toe Book Excerpt

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Hypoglycemia (Low Blood Glucose): Diabetes Head to Toe Book Excerpt

Dr. Rita KalyaniContributor:  Dr. Rita Kalyani, MD, MHS

Most people with diabetes, at some time, experience the symptoms that occur when blood glucose levels fall below normal—a condition known as hypoglycemia. For many people with diabetes, the symptoms of hypoglycemia start to occur at a level of 70 mg/dL (3.9 mmol/L) or less, but this level may differ for each person.

What You Need to Know

Though hypoglycemia can be common and occur repeatedly in some people with diabetes, symptoms of low blood glucose should always be taken seriously. You may have one or more of the early symptoms listed here:

  • Early signs of hypoglycemia: sweating, shakiness, racing heartbeat, flushed face, anxiety, irritability, or hunger pangs.
  • Late signs of hypoglycemia: headaches, blurred vision, sleepiness, dizziness, lightheadedness, confusion, difficulty speaking or eating, seizures, or coma.

However, sometimes persons with repeated bouts of low blood glucose eventually don’t feel any symptoms, a problem called hypoglycemia unawareness. A continuous glucose monitor may be helpful for these persons. A critically low blood glucose level is considered to be less than 54 mg/dL (3.0 mmol/L) and can lead to severe neurological symptoms, such as confusion or coma.

What Causes Low Blood Glucose?

In most cases, low blood glucose results from overtreatment, such as taking too much diabetes medication. Insulin and sulfonylureas (and meglitinides) are the medications most commonly associated with hypoglycemia. Delaying or skipping a meal can also deprive the body of glucose and lead to hypoglycemia. Eat balanced meals throughout the day and always keep a snack on hand, particularly if you are on these medications. Physical activity doesn’t just burn calories, it also burns blood glucose. Hypoglycemia can occur if physical activity is increased but the diet or medication is not appropriately adjusted (such as taking snacks or decreasing medication doses). Drinking alcohol (without food) or having an illness are other situations in which hypoglycemia is more likely to occur, and precautions to prevent low blood glucose levels should be taken.

How Can I Prevent Low Blood Glucose?

  • If you often experience low blood glucose, ask your health care provider if setting a higher goal for your A1C level may be appropriate.
  • If you’ve had low blood glucose levels, consider wearing a medical alert bracelet so that others will know that you have diabetes in the event of an emergency.
  • Keep a fast-acting carbohydrate in your bag, office desk drawer, car, bedside table, and other places for easy access. Good options include hard candy, fruit juice, or glucose paste or tablets. Snacks with about 15 grams of carbohydrates are good to correct hypoglycemia.
  • Monitor your blood glucose regularly so that low levels can be corrected before symptoms progress.
  • These precautions are also important to prevent low blood glucose levels while driving.
  • Own an emergency home glucagon kit, particularly if you are on insulin and have a history of hypoglycemia. Glucagon injection is an emergency medicine used to treat severe hypoglycemia in persons with diabetes who have passed out or cannot take anything by mouth.

What Does It All Mean?

Hypoglycemia usually occurs at some point in persons with diabetes and is commonly related to overtreatment (especially when taking too much insulin or other pills that stimulate insulin production, such as sulfonylureas), delaying or skipping meals, or exercising more than usual. Checking blood glucose levels as recommended can help prevent episodes of hypoglycemia before they happen. If symptoms of hypoglycemia occur, take a fast-acting snack that has 15 grams of carbohydrates to boost your glucose level, and let your health care provider know.


Diabetes Head to ToeDr. Rita Kalyani is an Associate Professor of Medicine at Johns Hopkins University School of Medicine in the Division of Endocrinology, Diabetes & Metabolism. She is an active clinician in the Johns Hopkins Comprehensive Diabetes Center. Dr. Kalyani directs the Diabetes Management Service for Johns Hopkins’ Total Pancreatectomy Islet Auto Transplant Program. She is a new member of the DiabetesSisters Board of Directors.

This excerpt is taken from “Diabetes Head to Toe: Everything You Need to Know about Diagnosis, Treatment, and Living with Diabetes” by Dr. Rita Kalyani, Dr. Mark Corriere, Dr. Thomas Donner, and Dr. Michael Quartuccio. This book is available for pre-order and will be published in November 2018. Published by Johns Hopkins University Press © 2018. Reprinted by permission of the publisher.