Type 1 Dawn Effect for non-pump users

I’ve been a T1D for 55 years and still going strong. For much of that time, the most wonderful technology was simply having access to insulin - in those early days, Regular before meals and NPH.

More recently the pace of tech improvements has quickened. Insulins are better, but for me the breakthrough was CGM or “continuous” monitoring (actually every 5 minutes, not continuous, but you can’t fault them for their marketing). I love what my Dexcom G6 allows me to do.

The other tech breakthrough is the insulin pump, which my Endo has offered to me, but I have chosen to wait. I get good control using Tresiba every 24 hours – talk ablut FLAT BG levels when fasting!) and Fiasp before meals or as needed. My background is info technology and I love the idea of closed loop systems, but I have chosen not to go with pumps until later.

So I discover from my CGM that I have been having Dawn Effect an hour or two before morning wakeup. Apparently the body has evolved to put out some hormones that have the effect of raising BG levels just before dawn. I suspect I’ve experienced this for most of these 55 years but just didn’t know it until CGM. I asked my Endo if there is a solution short of moving up to a CGM/Pump closed loop solution.

She said people are having success using a combo of insulin and a drug developed to treat T2D. She prescribed Metformin just before bedtime. Since it lowers BG levels somewhat, we dropped my Tresiba by 20%.

Looks like it is a successful solution – if I go to bed in the target BG range, my BG level stays essentially flat all night – no more Dawn Effect.

I do expect to go closed loop with pump someday, but for me, this is a perfect solution for now.

I tried metformin to try to reduce my total insulin intake.
I was awakened to the idea that a lot of insulin is not good for us.
I got the script, and took it for a month and I saw no change in blood sugar at all. I was very young at the time, maybe 25.
I don’t know if it would have a better effect now, but my daily insulin needs are almost identical to what it was back then.

If it lowered my insulin needs, I would reconsider it.

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I am early in my experiment taking 500mg Metformin at bedtime, but so far it appears I can take 17 units of Tresiba instead of 21 per day and while fasting, BG is in good range and flat. I do not need to take more short-acting Fiasp than I was for a given amount of food.

What amazes me is how each of us is different. What works for one doesn’t for the next.

I have no idea if Metformin would work better for you now. Would be nice if it did. My Endo prescribed normal Metformin, not extended release, since our goal was to try to eliminate the Dawn Effect.

Thanks for the note.



I’m Type 1, too, and have been taking metformin for about a year now. Supposed to be 500mg 2x day, but I’m pretty bad about actually taking it. I do think it helps cut back on my basal need, but not in a significant way. If it worked better, I’d probably be better at taking it. Metformin is supposed to work in 3 ways: increases endogenous insulin production, increases insulin sensitivity, and impedes the liver from putting out glycogen (what our basal insulin covers). There’s a lot of mixed opinions when it comes to us and Metformin, because the biggest advantage… making more insulin!.. doesn’t work for us. The question is how effectively it can do the second two. Since you only need a little boost at dawn, it’s probably a perfect choice for you. Personally, though, I find it disappointing.

I’ve got an appointment on Monday and I’m going to see about switching it out for a SGLT2 inhibitor instead. They’re approved in Canada for use in Type 1s, but not in the US. Obviously my doctor is on board with the off-label stuff, though, since she suggested the Metformin.
Theyy actually make you pee out more sugar, so you need less insulin. And as a benefit, they’re beneficial for the heart and kidneys. Sounds like a win/win to me. The downside is rare occurrences of DKA without elevated BG and about an 11% risk of UTI/yeast infections… But I’m not worried about those. I can handle the first, and I suspect the latter goes more with those who don’t have good numbers/TIR.

I’m also really curious about GLP-1 agonists (Trulicity, Victorlza, Ozempic,). They’re the other Type 2 drug that had been shown beneficial off-label to Type 1s. It scares me a little bit, though, since it slows your digestion. I’ve had a few erratic lows lately and I wouldn’t want to slow down treatment for them. I was leaning towards the GLP-1s until the other day when I forgot to extend my bolus for pork belly ramen. Insulin hit long before any carbs got through the pork belly, and I couldn’t do much but suck on honey and hope it absorbed that way. It got me worrying that every day might be like that on a GLP-1 agonist.

I think you are playing with semantics. Dexcom is advertised as a system that continuously monitors your blood glucose equivalent, which it does. The 5 minute interval period you are talking about is not a “monitoring” period, but the time interval between each point of display. A lot happens behind the scenes during that display interval period and the Dexcom algorithm smooths out the results and removes values outside a certain range it deems questionable or unreliable. A few years back, I did have a program that downloaded and actually displayed the raw data and I played with it to see if I could design a better algorithm custom-tailored to my body, as I have always been MDI, and plan to continue MDI for the foreseeable future.

My solution to the Dawn Effect was to eat OMAD, one meal a day at noon. If my BG rises more than 10 points in the morning, it is strictly the result of over eating at my one meal. I gain about 0.1 lbs for every 10-15 points of morning BG over the 10 from actual Dawn Effect. If you have a digital scale, you can prove that out for yourself as well.

That’s an interesting method you have, and linking weight to bg so specifically.
I lose more than .1 lb just peeing in the morning.
My weight fluctuates as much as 2 lbs per day depending if I’m exercising or eating etc.

Drawing a correlation like that would be really difficult for me.
The eating once a day thing would be doable if I lived alone.
I have a family and we eat together, there is an important social aspect to eating 3 meals. I eat small meals for breakfast and dinner.
There are thousands of diets and ways of eating, I’m glad that works for you.

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I get up, pee, weigh. Have to have a set routine to make this work

Of course I was playing with semantics, just making fun of the fact that we use the word “continuous” when in fact the system takes discrete snapshot measurements. I am very comfortable with the 5 minute choice. They could have chosen 10 minutes or 1 minute. 5 minutes is likely an excellent compromise between fairly frequent measurements and battery life. I am not at all criticising Dexcom’s design choices, only having fun with the marketing term. To be clear, I love my Dexcom CGM. If is really good technology and extremely valuable to T1Ds.

It’s interesting how this5 min number came up. I was one of the first people to try a dexcom in a trial. It was set to take readings every min. And they explained to me that it took the interstitial tissue 5 min to catch up, so it would be easier to run it at 5 min intervals.
The Original dexcom had to be plugged into a finger stick meter for calibration. And it waited 5 min before it accepted the calibration.
On top of that it uses up the battery faster so they landed on a 5 min interval. But in reality it is constantly creating a voltage and it is transmitted every 5 min.
The old systems were much less accurate and so there was no real benefit to taking readings every min, when I looked at the 2 sets of data, you saw a very nice smoothing effect from 5 min intervals.
That is an effect it still uses, as well as other algorithms to give trending information.
It turns out that 5 min intervals are really the best way to sample. Pretty sure all the sensors use the same protocols for that reason

Interesting background info. Thanks. It’s great the measurement of interstitial liquids was found to correlate well to actual blood glucose levels. And I’m glad they did not go for every 10 minutes, even if that would have extended transmitter battery life. Of course, it does not hurt Dexcom financials that the transmitter lasts only 90 days or so. But as the user, there are times when I really want to see that next reading, and 5 minutes is not long to wait.

I am grateful for what the G6 can do. My wishlist is pretty short: I wish the transmitter battery were rechargeable like some wireless smartphone rechargers. (I know, not gonna happen for profit reasons.) And I wish the sensors were more reliable during the first 24 hours. For me, some are, but many are not, and for those, I am forced to calibrate several times that first day. But that is a small price to pay for this excellent tool.

Back when I was on MDI they started me on Metformin for DP too. I’d been in the habit of taking some insulin at bedtime to knock my BG down and relying on DP to bring it back up to normal—kind of a risky/stupid juggling act. It worked ok as long as I had zero carbs for dinner, but not a good solution. Metformin worked somewhat, but really it wasn’t until I had a pump and could program a higher basal rate starting around 3 a.m. that I finally got control of it. But CGM is the real game changer. More important than a pump by yards.

The other T2 medication I might recommend is Jardience. My endo suggested it for me a couple of years ago and it’s made a huge difference in attenuating my spikes and drops and keeping my A1c down in the ~6.0 area.

Can you tell me a little about your transition onto it? Did you have to reduce your basal any, or does it mostly just work on meal spikes? Did you have a lot of lows after starting it? My doctor doesn’t know much about Type 1 and this stuff, but she’s happy to write the scripts I ask for so long as I can self-manage well… and this is the way I’m leaning. I’m trying to get my TDD down, but 80% of my insulin is basal. I don’t eat a lot of carb, about 100g a day, so it might not effect me much if it only really affects those post-prandials.

Does anyone else remember that the original transmitters lasted a year or more? My first one lasted 11 months and they gave me a free one because it didn’t last a year. They just allowed you to use them until they died back in the day.
That 90-110 day thing is built into it so we will buy more transmitters.


Titrated up from 5mg/day to 20 over period of about two weeks.

Lowered my basal as well as attenuated meal spikes.

Nope, but that’s why titrating up gradually is important. It takes a few days to build up in your system, so you need to give it a little time to see how you’re doing before taking the next step.

It definitely did that for me.

Same here.< 100 grams of carbs per day, and most of my insulin is basal. But it definitely helps with post-prandial excursions in both directions: less insulin means fewer hypos.


Thank you so much for that info!

I will check my old transmitters. I have them from day one, thinking I would replace the batteries, but never did. I believe I dated each box the day I started the transmitter, but maybe not with the initial ones. I’ll take a look and let you know.

I have found this sleep supplement to completely suppress my dawn phenomenon: https://typeadiabetic.com/supplement

I can’t vouch for how it will impact you, but I can share that I used to wake up around 140 and with it I wake up between 100-110. I suspect some if not many of the components in the formula suppress hormones that activate liver glucose production overnight.

I’d be curious if it has a similar impact on others…

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John – Very interesting about the Valerian Root Extract. Do you use a CGM? I’d be curious if your BG stays flat all night. In my case, once I got my CGM, I learned I was going high, then coming back down just before wakeup time. Metformin is dealing with that for me, but it has some mild side-effects and I am open to other methods.