Wil Dubois

Hi All -- Got questions about life with diabetes? Then you've come to the right place! That would be our weekly diabetes advice column, Ask D'Mine, hosted by veteran type 1 and diabetes author Wil Dubois.

This week, we have a timely summer question about just how much the beating sunshine might create a problem for those with diabetes, especially those who spend a lot of time outdoors?

{Got your own questions? Email us at [email protected]}


Jason, type 2 from Missouri, writes: I was just diagnosed with type 2 in the past year, and over the past several months have lost weight (40 pounds) and have been eating better and generally living healthier. I am not on insulin, only metformin. I just spent Saturday working 10 hours outside in the heat and it wiped me out like never before. I had no energy left by the end. So, does working outside in the sun and heat affect people with diabetes more than others? 


[email protected] D’Mine answers: First things first—your weight loss—that’s frickin’ awesome! Way to go! Woot, woot, woot!

Next: Having diabetes in-and-of-itself shouldn’t cause you any trouble working outside in the heat, although 10 hours outside is a hell of a long stretch. That would totally kick my ass. But I guess it’s a matter of what you're used to. If not that long ago—and 40 pounds heavier—you were able to have energy after 10 hours in the sun, then something new is going on, and we need to get to the bottom of it. On the other hand, if the last time you spent 10 hours outside working in the heat you were 20 years old, then all I have to say is: Welcome to middle age!

But assuming that up until recently you were an outdoor superman, I can think of at least three possible causes of your being wiped out like never before at the end of the day. And the first is your medication.

Although rare, photosensitivity is a documented side effect of met, which shows up around three weeks after starting metformin. Now typically, medication-induced photosensitivity manifests itself as wicked sunburn or bright light sensitivity. But if you were only mildly photosensitive to the med, it’s possible your body might react in a non-typical way. Mind you, this is a rare side effect to start with, so the odds of an atypical reaction to a very rare side effect are not something I personally would wager much money on.

Still, stranger things have happened.

But wait, there’s more. At least one study shows us that metformin can cause a slight reduction in what’s called peak aerobic capacity. Well… maybe. I say maybe because the study subjects were 17 normal-weight men and women who didn’t have diabetes. And they only took the met for a week, which, given the three-week window met needs to trigger photosensitivity in those who suffer from it, made me wonder if the reduction in exercise tolerance would have been more significant if the study had kept the subjects on the metformin longer.

But the bottom line is that although for most people there are precious few side effects from taking metformin, it is capable of causing you trouble. So how would you find out if it’s the met that’s kicking your behind, or something else?

With, and only with, your doctor’s blessing I’d suggest a trial break from metformin to see if your outdoor energy returns. You’d need to test your sugar more often and probably need to eat low-carb during this trial to keep your diabetes in check, although as you’ve lost a lot of weight, I’m betting your sugars have improved enough just from that for this test to be safe. 

Sunshine Smiley Face

Now looking in a different direction, there is a connection between type 2 diabetes and hypothyroidism, a condition where the command and control organ for your body’s metabolism gets sloppy on the job. It’s not as strong a connection as we see between thyroid problems and type 1 diabetes, where diagnosis of one mandates testing for the other, but type 2s still have significantly higher rates of thyroid trouble than do the general public. This is something definitely worth investigating because having no energy left at the end of the day is a primary warning sign of a lazy thyroid. A simple blood test ordered by your doc will get to the bottom of it in 24 hours. If your thyroid is out of whack, you’ll need to take a booster pill to get it back on track.

And my third thought has to do with energy management. In general, you’d expect someone who lost 40 pounds to have heaps more energy than they had before they lost the weight. After all, being 40 pounds overweight is like carting around a five-gallon water cooler jug, or two car tires, or four bowling balls, with you all day everyday. Hell, 40 pounds is eight Chihuahuas, and no one in their right mind would carry eight Chihuahuas around if they didn’t have to.

But… and there’s always a but… you had to lose that weight somehow, so I’m guessing you’ve made some changes to your diet, as the only effective way to lose weight is to consume less energy than you burn.

I think you might see where I’m going with this.

It’s entirely possible that your new levels of calorie consumption are adequate for a run-of-the-mill day, but simply not enough fuel to carry you through working 10 hours outside in the heat. You might have ended your day wiped out simply because your body didn’t have enough fuel to carry you through the day.

Obviously, your diet is working well for you overall, but you might need to eat a bit more for those superman-in-the-sun workdays.


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.