Got questions about navigating life with diabetes? Ask D'Mine! Our weekly advice column, that is — hosted by veteran type 1, diabetes author and educator Wil Dubois.

This week, Wil gets to hear about how his past advice helped a fellow PWD, and who now faces another challenge related to her diabetes management while under water in the Land Down Under. So, come on in for a read -- the water's fine!

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Marianne, type 2 from Australia, writes: Hi Wil! A year or two back, I had a question about taking up scuba diving with diabetes. Well I've taken your advice and I've enjoyed every moment of it. But I'm now experiencing a problem and I'm hoping you've got some more advice to offer. My blood sugar drops too low and too fast when I'm diving. I went for a dive a couple of weeks ago and managed to get my levels above the 8.3 mmol (150 mg/dL) that is the recommended minimum before entering the water—though my doctor suggested that this recommendation is more for my Type 1 cousins rather than for us T2s. I tested immediately after I got back on board after 50 minutes in the water and my level was 3 mmol (54 mg/dL)! The person who conducted my open water course also has diabetes and he was standing right behind me when I tested. We were both shocked!

Since then I have seen a dietitian who recommended fruit juice and baked beans to raise my blood sugar before the dive, amongst other things, but these were the best options to take onto a smallish dive boat. I took this plan to my doctor, who is certified to give dive medicals, and also pretty good on the diabetes side, and he approved. For one reason and another, my first dive of the day on my next trip out lasted only 25 minutes. I got back into the boat at 4.4 mmol (79 mg/dL). Not as bad at the 3 mmol (54 mg/dL) but the dive didn't last as long either. Do you have any suggestions about other things I might try to raise my sugar levels? I'll keep my fingers crossed for an encore performance.

Wil@Ask D'Mine answers: Great to hear from you again, Marianne! Thanks for the update on the diving and I'm glad my advice helped. It's wonderful to hear that it worked out so great for you! Now as to this new issue... With respect to your medical team, I think they're barking up the wrong tree. No, wait. No trees or dogs in the water. Oh crap! Being landlocked for so many years has left me unequipped to deal with high-seas metaphors!

What I'm thinking is that maybe you don't have to raise your blood sugar at all before going under the waves, because I'm not convinced the problem is a real one at all.

Steer this course with me for a while before you bail on me.

Now I'm inferring from the fact that you were "shocked" that your sugar was so low, that you didn't feel any symptoms of being low. I also know that, although we edited it out of your published question for the sake of space, that your doc reScuba Divingcently lowered your only blood sugar med, metformin, to 1,000 mg per day because you are doing so well on your diabetes control. Good for you! Everybody, give our scuba-diving type 2 cousin a round of applause for this achievement!

Anyway, the reason I mention this is that it's pretty damn rare for folks on metformin to have lows, like maybe 1% of users ever get lows from the med, and the lower the dose, the more scarce that rarity becomes. The reason for this is because of how we think metformin works. I say "think," because we actually have no frickin' clue how this drug works. Metformin trivia: Did you know it's been in clinical use for more than 50 years? That it's now the global standard for front-line diabetes care? That, other than insulin, it's the most effective medication in the medical arsenal for lowering blood sugar? It's safe, effective, and cheap.

But while metformin's been under the metaphorical microscopes of over 13,000 clinical researchers during the last 60 years, and has been the subject of more than 5,600 published studies, we still don't know how it works. WTF?! There's even an entire book written about this medication. And yes, I've read it. And yes, it IS probably the most expensive book in my library. Oh. Wait. That's a lie. Some of those beyond-lovely, gold-gilded, embossed, leather-bound hard-cover classics from Easton Press have set me back more. Whiskey, women, and books. There are worse things to be addicted to.

Oh dear. I've really gone off track. Or is it off the deep end? I'd better come up for air.

Back to metformin. So how can you get a drug approved if you don't even know it's method of action?

Well, it was developed back in the days when you did clinical research by feeding rats anything you could find, and then sat back and watched the results. OK, I over-simplified that a bit, but pharmaceutical research has come a long way in the last few decades. The trial-and-error method of drug development has been replaced with a more focused molecular physiology approach.

But while we don't really understand exactly how metformin works, we know how well it works, and what it does and doesn't do. And one of the things it doesn't seem to do is to cause low blood sugar.

So let us consider the facts. You're on a very small dose of a drug that very rarely causes low blood sugar. You're doing an activity that you've done a number of times with no problem. You had no symptoms of a low.

Maybe you didn't have one at all.

We know that there are any number of things that eff' with our glucometers... but could saltwater? I simply don't know. And when I did Google searches for "saltwater and blood sugar testing" I mainly got results dealing with the effects of eating saltwater taffy. In fact, I couldn't find anything anywhere to back this up, but I think something about the dive environment caused your meter to give you a false readings. Maybe the residual salt on your fingertip threw off the strip. Maybe the humidity threw off the meter itself. Maybe the tangy air of the sea breezes...

So try this on your next dive: Keep your meter in a zip lock bag. Keep it in the shade. Make sure you didn't take your strips out of the little canister early to save time (there's a reason for the canister, like leaving raw fish in the sunshine, strips go "bad" quickly out in the air). Rinse your hands with fresh water before testing, then make sure they are very dry. And take a meter and strips with you that are a different brand from what you normally use -- see if you can score a sample from your doc, and then test with both meter systems and compare the results. I predict this will drown the "low" blood sugars.

Of course, there's one other remote possibility. Perhaps your efforts to raise your blood sugar to type 1 diving levels might actually be counterproductive. Here's how that works: In some people, if they eat a much larger than normal meal, the pancreas panics. It says, oh my God, I've never seen so much sugar! And it responds with a flood of insulin. Now, normally, the body is a pretty good judge of how much insulin is needed; and if it's wrong it can always tap into some sugar from the liver to balance things out. That said, this massive spike of first-phase insulin in response to a much higher than normal carb meal is one of the few things that can cause endogenous hypoglycemia, in other words a hypo caused by your body, not by meds. Even though this does happen, it's pretty damn rare. I've seen it a couple of times when we bring folks in for fasting oral-glucose tolerance tests. Hi there! Have a seat. Here, drink this two-gallon jug of Kool-Aid. Faster. Chug it!

There's only so much a body can handle.

But that said, this type of response is normally seen only in very thin people. And you've told me you don't fit in the category of "very thin." Still, your weight makes me skeptical about your attempts at raising your blood sugar pre-dive being the trigger behind the lows—if they exist at all.

Oh, and because some of you are wondering, some of the other causes of endogenous hypoglycemia are insulinomas (tumors in the pancreas that trigger over-production of insulin); liver diseases such as cirrhosis, a couple of bizarre pituitary disorders, and the all-you-can-eat breakfast at Waffle Hut. I'm nzebraot worried about any of these in the case of Marianne, because she's only having lows when she's diving and there's no Waffle Hut on her boat. I know because I checked.

So I'll still put my money on a seasick glucometer. I just don't think your body is set up for a hypo response to a big meal; your meds are unlikely to trigger a low; and there's the Zebra Rule of medicine. That rule says that if you're walking in the woods and hear hoof beats, it probably isn't a Zebra. (This assumes the woods you're walking in aren't in Africa). In other words, while all kinds of crazy things are possible, most of the time, the most likely explanation is the right one.

Anyway, try the various steps we talked about above, to rule out meter trouble, and I'll bet it'll be smooth sailing on the Seven Seas. Well, under them.


This is not a medical advice column. We are PWDs freely and openly sharing the wisdom of our collected experiences — our been-there-done-that knowledge from the trenches. But we are not MDs, RNs, NPs, PAs, CDEs, or partridges in pear trees. Bottom line: we are only a small part of your total prescription. You still need the professional advice, treatment, and care of a licensed medical professional.

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This content is created for Diabetes Mine, a consumer health blog focused on the diabetes community. The content is not medically reviewed and doesn't adhere to Healthline's editorial guidelines. For more information about Healthline's partnership with Diabetes Mine, please click here.