The Case of the Club Med Scuba Instructor Whose Blood Sugars Took a Dive!

Dr. E's Case Study

The Patient:

Ethan is a 22-year-old male who has had type 1 diabetes since he was seven years old. He’s been on MDI since he was diagnosed because he’s always loved the water, and it’s been easier for him to use that regimen. After college Ethan got his dream job working as a scuba instructor at a Club Med resort in the Caribbean. He conducts two group dives per day – one in the early morning around 8:00 a.m. and one in the late afternoon closer to 6:00 p.m.

The Regimen:

Ethan uses a long-acting basal insulin (Lantus) and a fast-acting insulin (Novolog) for boluses. He wears the Eversense E3 CGM because it’s inserted under the skin, and the overlying transmitter that sits on the skin above the sensor insertion site doesn’t have to be removed when he dives (depending on the depth).

His CGM downloads are below. The top chart is his 14-day download and the bottom chart is a 24-hour glucose profile.


Ethan's Eversense CGM Download


Ethan's Eversense CGM Ambulatory Profile

Ethan’s average glucose is 125 mg/dL (goal is less than 154 mg/dL). His estimated A1c (called GMI) is 6.3% (goal is less than 7%). His glucose variability is 32% (goal is at or below 36%). His time in range is 81% (goal is above 70%). His time above range is 11% (goal is less than 25%). His time below range is 7% (goal is 4% or below).

The Problem:

As you can see from the 24-hour glucose profile, Ethan would get low around 8:00 a.m. and then again around 6:00 p.m., which was when he was scuba diving. He still got his vibratory alerts while diving because the Eversense will vibrate up to 33 feet underwater.

The Solution:

I made the following recommendations to Ethan to help him avoid lows while he’s diving:

  • Reduce his basal dose by 5 to 10%
  • Change his basal insulin from Lantus to Toujeo as it is a better flatter basal insulin without any peaks
  • If meals are within 2 to 3 hours before diving, reduce mealtime bolus by 20 to 30%
  • Consider trying inhaled insulin Afrezza pre-meal because it gets out of the system faster than injected insulin
  • Have appropriate pre-exercise meals/snacks with protein, fat, and carbs such as peanut butter and crackers. Carbs with protein and fat will stay in the system longer than just plain carbs and will help prevent hypoglycemia over a longer period of time.
  • Educate his coworkers on how to recognize and treat hypoglycemia with a glucagon pen like Gvoke

I have also started counseling all my patients with type 1 diabetes about the recent availability to test first and second-degree relatives for type 1 autoantibodies. People who have a first-degree relative (parent, sibling, or child) with type 1 have an increased risk (up to 15x) of developing it themselves. You can read more about screening and early treatment options here.

The Takeaway:

Living with diabetes shouldn’t stop you from pursuing your passions. With all of the options we have today when it comes to CGMs, insulin types, and insulin administration devices (pumps, pens, etc), you can likely find a regimen that will work with your lifestyle, favorite sports, and activities. Ethan is doing great now, but I still might have to move to Club Med to keep an eye on him!


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    I did not know the Eversense would vibrate a low alert under water. That’s AMAZING!

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