Wound Care Articles and Insights
November 16, 2020

Hyperbaric Oxygen Therapy and Hypoglycemia in Patients with Diabetes

Norma Marlowe

Hyperbaric oxygen therapy (HBOT) is often used as an intervention for non-healing diabetic foot ulcers. During treatment, a patient breathes 100% oxygen intermittently while inside a hyperbaric chamber at a pressure of up to three times higher than normal air pressure. Wounds need oxygen to heal properly, and exposing a wound to 100% oxygen can, in some cases, speed the healing process. For patients with diabetes, this can also present some concerns about glucose levels.  

Hypoglycemia: An Observed Phenomenon

Wound care practitioners often observe that patients with diabetes experience a drop in blood glucose levels during - and immediately after - HBOT. While this phenomenon has not been extensively studied in a systematic manner, it is often reported. For a wound clinic, this can mean canceled or shortened treatments - and the resultant scheduling and operational challenges. For the patient, hypoglycemia can mean a delay in receiving limb-saving treatment. For these reasons, treatment facilities must have a clear policy in place that outlines regular glucose measurement and interventions for diabetic patients, and they should routinely provide them with ongoing support and nutritional education information.  

Low Glucose Levels Prior to the Hyperbaric Oxygen Therapy Treatment Session

Wound care patients with diabetes should routinely have finger-stick glucose levels tested upon arrival for treatment. While there is no universal cut-off number for treatment cancellation, any result less than 120 mg/dL warrants further evaluation. Factors to consider: the duration of the HBOT session, the type and time of administration of anti-diabetic medications, and the patient’s history of blood glucose control and tendencies for hypoglycemic reactions.

If a patient presents with a lower-than-desired glucose level, the obvious intervention is to increase it prior to treatment. Anecdotal stories include patients who report being given candy, soda, or a large glass of orange juice to quickly raise their glucose levels so they can proceed with a scheduled treatment as planned. This practice must be halted because it is not safe. Not only does it provide a mixed nutritional message to the patient, it may or may not be able to sustain the patient throughout their entire treatment. A quick spike in blood glucose can drop just as quickly as it rises. It would be much better to have a more comprehensive and proactive approach before treatment.

Oral nutritional supplements (ONS) designed for patients with diabetes are a much better choice to increase blood glucose. They provide a mix of protein, carbohydrates, fat, vitamins, and minerals that promote a slower rise in glucose levels, as well as a slower decline than candy or other high-sugar foods and beverages. In other words, a balanced blend of macronutrients leads to less fluctuation. For patients undergoing longer HBOT sessions, this is important because glucose levels can fall while the patient is in the chamber, leading to other serious consequences. ONSs are also convenient and ready to serve. For hypoglycemic symptomatic patients, a fast-acting glucose gel should be used quickly raise blood glucose levels.  

Teach Your Patients Well

Talk to your patients about consuming nutritionally balanced meals and snacks prior to HBOT, and why it’s important to eat regular meals throughout the duration of treatment. Patients need to be involved and understand that it’s beneficial to their progress if they routinely arrive at the clinic with appropriate blood glucose levels.

In addition to HBOT, a well-controlled hemoglobin A1c level is also important for better healing. Educate patients on how to limit simple sugars, eat less processed foods, and spread carbohydrates over the course of a day and consume them as part of a balanced meal. If more detailed education or support is needed, a referral to a registered dietitian nutritionist (RDN) is warranted. Diabetes self-management education is often covered by insurance, especially for newly diagnosed patients with diabetes.

The Importance of Setting Up a Protocol

All wound care programs offering HBOT should have a nutritional protocol in place. If you don’t have one, now is the time to evaluate your approach to monitoring and educating patients with diabetes. Create a system for your patients designed to address and minimize episodes of hypoglycemia. A combination of nutrition education, proactive glucose monitoring, and appropriate interventions to raise blood glucose are the foundations for a better healing journey.  

About the Author: Nancy Collins, PhD, RDN, LD, NWCC, FAND, is a wound care-certified, registered dietitian nutritionist with expertise in wound care, malnutrition, and medico-legal issues. Dr. Collins strives to improve patient outcomes and patient satisfaction through better communication. To contact her, visit her website,

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