Novolog - how long until it begins to work

I'm still relatively new at this T1-like diabetes, and I know one of the things I should check is how long it takes for the Novolog to start working, so I can inject it the optimal amount of time before I start eating. So I took a dose of Novolog (2.5 units) that I needed to correct a high BG, and started testing, every 5 minutes. The instructions I read somewhere said "test until the BG goes down 10 mg/dL." Well, I tested every 5 minutes for quite a while, during which time the reading was the same - give or take a few notches up and down. Until 50 minutes later - whammo - it went down 25 mg/dL! Is this normal? Should I try it again? And what does it teach me - how long before I eat should I take the insulin shot? Thanks!

I have done this too. When I need to bring a bg down just say from 9mmols to 6mmols, it often sits there for a while and then maybe half an hour later I crash. Lots of people here will be able to explain why this happens. With me it can be anything from the exercise I've done, where I inject, what I ate at my last meal.

Here's a graph showing the action times of various insulins. It's not guaranteed. When I got my pump either the doc or the SalesNurse mentioned that NPH has only a 53% chance of peaking when it's supposed to so you can get all sorts of interesting combinations with that!

it generally starts peaking in 30 min. I doubt that checking your blood every 5 min is really worth while. It wont change that much in 5 min. I think checking every 15 is more likely and I wouldn't even bother for myself for 30 min because I know how my body works.

I usually bolus 30 min before I eat and it usually works nicely. The trouble with trying to correct high sugar after you have eaten is that the insulin you already took probably has not had time to finish its work, and if you add to it, your sugar can plummet at some point.

Eventually you will work out how much insulin you need for each meal or amount of carbs, then you wont have this roller coaster of ups and downs. It just takes time to work it all out.

I usually take a shot and wait about 15 minutes before eating. And while a CGM will check every 5 minutes, my blood sugar doesn't change that much in 5 minutes. I would say since the 15g/15minute rule is what you do for lows, I think you could use that same rule to test how quickly novolog works for you. But that changes with time as well. In the beginning when you are honeymooning and taking small amounts of insulin it may work more quickly also it depends on the time of day. Early in the morning I find I am more insulin resistant my I:C ratio is 1:5 and I usually wait a good 30 minutes before having breakfast, lunch and dinner I wait 15 minutes or so but as with everything else with D, YDMV, your diabetes may vary. Some people can take a shot of lantus and it will last all day and night, others have to split their doses. Some people actually will start eating before they take a shot.

Another novolog question - does anybody else find that one unit doesn’t do anything at all? What is the minimum that brings down your bg? And if I took one unit and my bg stayed the same, if I take one more an hour later will it act like one or two?

I find a unit can get quite exciting, depending on what else is going on. If your basal is a shade low, it might not do anything. If you have “food on board,” or had a shade too many carbs, same thing…there’s always this quilt of things and, a lot of times, it’s like “all of the above!”

Yes there are definitely times when it seems a single unit doesn't do a damn thing. Or it doesn't work as quickly as I want it to so I am waiting for my blood sugar to go down and waiting and waiting. The inclination is to just take another unit since you don't think the first one is working, but have some patience. If you take another unit it is called "stacking" and what will eventually happen is your blood sugar will plummet. And you climb back on the roller coaster again. So just relax and let it work, it will eventually and you won't have that crashing low that comes from impatience.

I think doing this sort of testing is helpful, but perhaps not in the way you think. First, we define a "perfect" meal bolus as a bolus that returns us to our normal preprandial number 3-5 hours after our meal. But that doesn't mean that you won't have blood sugar excursions, we mostly have highs, but sometimes you can have a low (such as from injecting too early). So we define the "perfect" bolus timing as the timing of the injection to minimize the maximum rise (or fall) in blood sugar. If you eat pure glucose, your blood sugar will peak within like half an hour. If you eat a mixed meal, you may peak at an hour (or later). You time your injection to do this.

When you do a meal test like you have done, you are seeing the combined effect. The 25 mg/dl drop simply reflects that your food is mostly absorbed while your insulin is still active. It doesn't reflect an onset of action at an hour. I will usually inject 15 minutes before a meal, but sometimes for a really low carb, fatty and proteiny I find it better to inject after the meal. It just matches the blood sugar rise more closely.

And yes, most drugs have what is called a physiological dose, a minimum dose required to observe any action. A single unit does nothing for me (mostly). If you still have some insulin production left, injecting a small dose (like a single unit) will simply offset the required natural production. Only when your injection starts to "supplement" your natural insulin production will an effect be observed.

When we inject insulin Sub-Q it has to saturate our body in order for some of it to find it's way and take effect. The Pancreas is wrapped around the vein that supply's blood to the liver so we respond to endogenous insulin almost instantly.

The size and makeup of our body has a big impact on how much insulin it takes, how long it remains active, and how much actually is utilized before the renal system has removed it.

One unit of insulin can lower my BG about 25 mg/dL but this is not static it's just a average and there are many factors that can effect my sensitivity, active insulin time, and IC:? ratio.

A tool like can help to show you what happens to your BGL after you take a dose of insulin, or a second dose one hour after the first with insulins overlapping.

Maybe everyone is different we did a check and it was about 20-25 minuites that mine starts working.1 unit does not do much for me either .