Basal timing

Hi everyone,
If my blood sugars are rising at 8pm what time should I adjust my basal insulin needs? My doctor recently told me 6pm but I was always under the impression that basal insulin affected blood sugars 4 hours after. Which do you use 2 or 4 hours for basal adjustments?


There are lots of factors other than timing like the type of insulin itself. Lantus lasts 24H at high doses so for example i take 9 at night(10 PM) and 2 in the morning (6:30 am) and it tends to wear off around 6 pm and my BG starts to go up.
I hear Tresiba actually lasts 24h but never tried that since it’s not available in Australia.
Levemir lasts like 18 hours hence most people taking it split doses equally to have it active around the clock
Also most of the long acting insulin you take at night is countered by the dawn phenomenon so not much of it is left by the afternoon.

I would try what your Doc recommended.You can always change it. Do several checks to see what time it kicks in

Generally you want to adjust 2 hours before the change is needed for Humalog or NovoRapid/Novolog. 4 hours was for Regular insulin which no one typically uses in pumps anymore. If you are using Fiasp it’s 1 hour before in my experience, and I’ve never tried Apidra so not sure if that would be quicker. These are just guidelines though, ultimately you have to make adjustments based on the results through trial and error.

What time do you eat dinner though? Another thing to consider is that you don’t need more basal but part of your dinner is digesting hours later after your bolus has worn off. Many meals can digest for hours, not just pizza and pasta as we’re often taught.

With an insulin pump using Apidra insulin, I have found that adjusting basal rates two hours before any hoped-for blood glucose change works consistently well for me.

Having said that, as a user of an automated insulin dosing system that can adjust basal rates every five minutes, I witness BG changes in response to basal rate changes within 15-20 minutes of the change. I’m not sure what’s going on here and I was surprised to see this phenomena.

I would start with the 2 hour mark. You can always increase. I use the 4 hour mark for correction insulin only.

Thanks everyone. I use humalog; soon to be novolog. I think my insulin to carb ratios are off a bit. I’m working through it. It’d be easier if two days in a row could ever be the same :slight_smile:

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Most of the books I have in my reference library say to make the adjustment two hours before you want the change to happen. Of course each of us is different but it might be a good place to start and make adjustments as needed. Good luck!

Thank you Sally!

Yeah, I hear you on that one! And this is what makes basal testing a little bit challenging. Because you should only make changes if you see a pattern. And most recommend at least three days to test. But wow, that is hard to do sometimes! Not eating for a time frame for 3 days. And than when you get three clean daysto use, there is no pattern. So frustrating sometimes!
And just a side note to basal testing. The key is, if the blood sugars are holding steady and not going up or down, it is set correctly. The hard thing for many if if the blood sugars are flat and at 180, that basal is correct because the blood sugars are flat. Once you get it flat, than you work on carb ratio to help with the higher than you want flat line. Your basal rate really isn’t designed to lower blood sugars, just to keep it flat.
Have fun! And sorry to say, just when you have it set, something in your life will change which means more adjustments.

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You are absolutely right! Well said! Thank you for the reply :slight_smile:

I’ll add one caveat - some meals eaten at dinner or before bed can digest for hours and cause higher basal needs all night. Whether this should be dealt with using extended/square wave boluses, temporary basal increases or permanent basal increases isn’t always clear, and I suppose part of the reason for looping pumps is to address this.