Adjusting basal rate ...?

When adjusting basal rates, what is considered a safe ‘increase’? My night time basal must be ok as my CGM gives me almost a flat line from bedtime to morning. However even when I don’t eat or I sleep later than usual, my BG climbs 30 to 40 points. My night time basal rate on my pump is 1.2 starting at midnight. The next rate is 1.1 starting at 6 a.m. (assuming I get up around 7 a.m.). The increase in BG seems to start around 8 a.m. Thanks for any help you have time to offer.

If I recall, Walsh in “Using Insulin” recommends a 10% change. It sounds like you just need a change in your morning rate. You may have to experiment, a slight change may suppress your Darn Phenomenon quite readily, or you may need to work up to a more aggressive increase. It is always a good idea to make a change to your basal and then monitor the effects of those changes for several days, perhaps a week before making any conclusions about it’s effect.

Thank You bsc for your help. I don’t have that book by John Walsh, but it sounds like I should make a trip to our local bookstore to buy it.

I never adjust more than 10% at a time. Then test it out for a few nights (at least 3) and change it again if needed.

If your BG consistently begins increasing at a specific time, you want to up your basal beginning half to one hour before the increase (with Humalog, less with Apidra) to give the new rate time to take effect.



Ex) My BG was beginning to raise at 9am and leveling off by 11, so I increased by 10% beginning at 8am until 10am, where I left the previous rate as is. I ended up increasing by a total of ~20% from 8am to 10am and I stay relatively flat now from 9am on. I hope this helps. Good luck! Figuring out basal rates can be an annoyingly frustrating process.


If you are pumping, that the book by Walsh called (amazingly) “Pumping Insulin,” that is tailored specifically to the pump. It does make a difference.

Does the 10% change rule apply when I need to reduce my basal rate (when I consistently go low at a certain time of the day)?

Actually, John Walsh recommends changing basal rates 3 hours before the time when you see the rise.

I don’t know that there is a 10% change “rule”, Mayumi, but it’s just better to be conservative as a small amount can make a big difference, whether to high or low numbers. I always keep careful note of the changes I’ve made and the results I’ve had so I can evaluate whether I need to increase or decrease again. In my initial setting of my basal rates for my pump which definitely took weeks to get perfect, I also had to play around with the time frames and ended up with 6 different “time zones” to get my numbers where I want them.

My educator told me a change less than 0.2 was a waste of time - which is contrary to this 10% “rule”.
Looks to me like you should start by delaying your second rate by 2 hr, rather than changing anything. But, I have “dawn phenomenon” really bad - my basals are similar to yours. I just give myself 2 u when I get up - in my case my BG rise immediately after I get up, so by giving myself 2 u instead of changing the basal I can get up whenever I want and not always at the same time.

I sort of disagree with your educator calling <.2U a “waste of time”. If you try a .5U basal bump and it doesn’t produce any change, you will have learned a fact about that particular adjustment that you can use? I don’t think that any data is a “waste of time”, whether it’s an actual result or a ‘negative’ in that your ‘test’ doesn’t work. General Chuck Yeager didn’t break the sound barrier the first time he tried, he worked his way up to it?

I get pretty decent adjustments w/ .05U/ hour adjustments? I am sort of a psycho about it, trying to keep my BG slightly < 100 most of the time. Occasionally it will drift up or run low, sometimes I’ve noticed it when I change exercise modalities, and I can see the difference in numbers w/ .05U/ hour, this out of a TDD for basal of 33.37 (30 day avg w/ 52% of insulin from basal…).

My endo and I change by 0.1 units in either direction at a time. I usually aim to start the change two hours before I am seeing the rise or fall. I would try increasing the 1.1 to 1.2.

I am always amazed at how much of a difference 0.1u per hour makes!!

Everybody’s body is so different. What do I do when I need to tweak basals - I just go to a different pattern, make the change I feel I need to try, run it for 2 to 3 days (or more) to see if I corrected correctly or not, and adjust from there. When I get something in that pattern I am comfortable with, then I go back to by standard and reset to all the new changes. That way I always know where I was before I began working on the tweaking. I have 6 rates, 12a, 3a, 6a, 9a, 12p, and 9p. Usually for me, the timing of the rate change is good, I will just need to adjust the insulin amounts.

Walsh also covers CGMs in the book. My summary of his chapter about CGMs: “Why did you buy the book? This book is for people who fly blind!”. I totally see the value of the book when all you have is 10 BG test strips per day. Then it is all about how to get the most out of the limited number of tests. With a CGM things are so easy. If BG is not flat while not eating adjust basal. I agree with your recommendation to take it slow. There is no rush. Recently my basal requirement changed. For almost a week my dex woke me up a couple of times per night and I ate glucose tablets to fix the lows. Eventually I gave in. I love my dex. It only wakes me up when things go wrong. I don’t have to get up at night to check that things are OK.