Pump vs. MDI and Dawn Phenomenon

Although I've been a Type 1 for 12 years (and on a pump for 11), I've never had this adequately explained. Is there a difference for those on a pump vs. MDI when dealing with dawn phenomenon? I think I read here that it is more pronounced in those on MDI vs. the pump. Is this true? Also, I know the standard time often discussed for this issue is 3 am. Does anyone else experience it earlier/later? I'm trying to get a handle on why-especially if I bolus after 7 pm or have to make a correction before bed-my bs will be ridiculously high (much higher than what I corrected) around 2 am. If my bs is stable before bed and I make no correction/have no residual IOB, my fasting numbers are perfect. Anyone have any advice?

Modern rapid insulin have a duration of action of 5 hours. If you do a carb bolus or correct after 7pm, do you really go to bed with no IOB? Darn Phenomenon (DP) usually sets in when your body clears insulin around 3-4 am and then releases cortisol, thus raising your blood sugar. Unless you normally get up at like midnight - 2am, it is unlikely your problem is DP.

Have you thought about whether you are having a low while you are asleep and your 2am high is actually rebound? I'm also not totally familiar with your insulin pump, some pumps don't fully account for IOB when stacking insulin. Is it possible when you carb colus or correct late at night you end up with stacking and have a low? You could test this by waking at midnight or so and checking your blood sugar.

The difference with a pump is that if you have a regular dawn phenonmenon rise in the AM, you can program a higher basal rate to cover the DP rise. With MDI, I think the insulins are "flatter" so you don't have anything to cover it with, except maybe adjusting the timing of the long-term insulin shots so that if they have peaks, they hit while the DP does?

Hi tebbemae. It works out for me pretty much as AR described. On my pump it was easy to get my basal set correctly, but I had to tweak it with changing seasons, etc. Now that I'm on MDI, my split dose of Levemir does just as well with respect to the DP. I'm quite sensitive to peaks in Levemir (and Lantus when I used it), but it works perfectly by taking Levemir at 9:30 PM, again tweaking for seasonal changes. (Levemir does not cover 24 hours, so almost everybody takes a dose in the morning as well as at night.)

Although I am on MDI, I also increase my basal dramatically overnight. I split my basal dose and my nighttime dose is about three times my daytime. And it is true that a pump will really give you the ability to choose a any profile you need for overnight basal.

But this is to deal with your constant need for more basal insulin to fight off DP, it is not something I would use to address variable highs. I would just worry that if my blood sugar went high "sometimes," programming a marked increase in overnight basal might be a little risky.

It does almost sound as if your problem may be rebound rather than dawn phenom. If you bolus after 7 PM for food and then also do a correction before bed, you'd definitely be stacking, and you might definitely be going low and then rebounding. Also it's possible that your correction factor isn't quite right and that is what's causing you to go low, then rebound. The fact that you say that when you don't do a correction, your fasting numbers are perfect, leads me to believe this is definitely more of a rebound problem.

I'm thinking that maybe one way to test this out would be to test again a couple of hours after your bolus or correction and see if you're heading low. Like, if you correct or bolus at 7 PM, test again before bedtime, but don't overcorrect if it's just a bit high. And if you do correct, set an alarm to test maybe 2 hours after the correction, whenever that is, to see if you're going low.


Thanks everyone! I am consistently amazed at the wealth of information available on this site. You all are so knowledgable and I greatly appreciate everyone taking the time and energy to share it with me! From the responses I am guessing my situation centers on rebounding.

I experimented last night and found my basal rate very stable (last bolus at 5:30-checked at 7:30 154-checked at 11:00 146-no correction for either, checked at 4:30 140). I know everyone with diabetes responds differently, but is there a general rule for how much your bs will rise if you are low and fail to correct it? I am sure it depends on how low, how much IOB there is, etc. But I sometimes find if I snack at night and bolus or have to correct for a high bs before bed that my early morning readings (anywhere from 2-4 am) will be hundreds of points higher than before. I feel like hundreds of points is too dramatic of a response for my body to make when fighting a low-am I wrong?

Thanks Judy! I tried searching for this (but I am still new here and couldn't find it). Just curious why you switched from the pump back to MDI? That is a route I am considering and would like to hear your reasons for the switch and any advice on making that change. Any advice would be appreciated!

Hi, I'm on MDI and had no trouble stamping down the DP by changing my basal routine so that I take a large dose in the morning and a dose adequate for DP in the evening. Your correction before bed depends on what you're doing with the basal. Your correction is too high, leading to the liver pouring out its glucose and your resultant high. Remember these corrective doses last 4 hours sometimes and at night you often have more sensitivity.

Tebbemae, due to age, my body changed and I found myself without enough good pump sites to make it all worth while. Actually there are pros and cons for both the pump and MDI; one big pro for the pump is being able to fine-tune your basal. My A1C runs a bit higher on MDI, but overall I'm OK with it. (Umm, my name is Trudy!)

I think that the middle of the night highs can also come from delayed digestion. I’m not talking gastroparesis, just slow digestion of lower carb foods and larger meals combined with lower activity through the evening.

Like many Americans, I struggle with not eating too many snacks after dinner combined with watching TV rather than my higher activity level during the day. Sometimes I avoid evening carbs by eating things like nuts and cheese. Those are of course foods that can digest at 2:00AM rather than earlier in the evening when I have more active insulin. I try to use extended boluses for those foods, but it doesn’t always work out correctly.

I agree w/ the delayed digestion, I think that my digestion slows way down after I go to bed.

Trudy-sorry! (that is what I get for replying to this at 4:30 am!) Were you initially on MDI before the pump? What insulins do you take now? You said your numbers run a bit higher-how much? I am really torn concerning my decision to remain on a pump or switch to MDI.

Hi tebbemae. I have to start by saying that I'm approaching 82 y.o., so my experiences are going to be somewhat different from yours. Still, Diabetes is Diabetes, the pump is the pump.

When I was first diagnosed my numbers constantly swung high and low, and I had quite a few dangerous lows; this went on for a few years. When I went on the pump I learned all that good stuff about carb/ratios, how to set it for perfect basals, etc., (actually, things that people are learning now on TuD without a pump). My A1c's ran in the high fives. I went off the pump gradually after about 8 years on it, wearing it only on weekends. My A1c's gradually crept up to 6.3. Now that I'm on MDI all the time, it's remained stable at 6.3. with no more wild BG swings.

I have Celiac Disease, so that I can't eat wheat, barley, or rye and also I'm intolerent to corn, soy and some nuts. With a rather restricted diet, I decided to eat moderate carbs, around 50-100 daily, rather than low carbs. On low carbs, I'm sure I'd be back in the fives, but I've decided I'm going to gluten-free beer on these hot days, a slice of Udi's bread now and again, but eat lots and lots of veggies, salads, meat and poultry -- moderate rather than low.

Your carb choices will affect your numbers as well as whether or not you are on a pump. However, I'm sorry that I can't wear the pump because not only was my control better, it gave me more freedom. Oddly enough after almost 20 year of Diabetes, I make a little insulin in the afternoon, so I have to work hard on my basals. This means my dose of Levemir (and Lantus and NPH before) are split three ways: 9:30PM dose for the dawn phen., a small dose at 7:30AM and another at 2:30PM.

Don't hesitate to experiment, I wish you the best of luck. As folks around the DOC are fond of saying: You can do it!