How fast should a fast acting insulin like Novolog be. For me Novolog takes more than an 90 min to act. So when doing carb counting, I have to take it atleast one hour before I eat, which is not practical for me. I thought fast acting should be immediate. This morning I had corn flakes and my sugars spiked, even though I took novolog, it was after 90 min my sugar started to come down.
I would consider, Sharif, that it isn't that the insulin isn't acting, but that it's insufficient insulin to cover the carbs ingested. 90 minutes is a fairly average time for blood sugar to spike from food.It is normal to have some rise in blood sugar after eating but the key is to take the right amount of insulin to keep it from going over your goal and to return to normal after about 3 hours. Do you have an I:C ratio? If you are always high at 1.5-2 hours you might want to tweak your ratio. Also, some of us find that cereal is one of those foods we can't accurately bolus for. I miss granola, fruit and yogurt for breakfast, but I tried enough to know it won't work.To answer your original question, many of us find it works well to bolus about 15-20 minutes before eating, but again, I think you might be confusing a normal spike (or too high spike) with the insulin action.
I'm not sure what that formula is, but it sounds like your I:C is 1:10. We are all different. There is really no formula for the "correct" I:C but the one that works for you. Many of us find we need different I:C's for different meals. Mine, for example are 1:6, 1:10 and 1:16. The only way to determine what's right for you is to eat something, test at two hours and see if you are within goal. (I use 140 as the number I want to be under at 2 hours). Then if you are always, high, you can take it up to 1:9 etc and take a few days to check before changing.
It would be ideal if there is no spike at all, but many Type 1's can't get that kind of stability. Personally, I'm content with staying under goal most of the time.
The performance of any meal-time insulin is significantly affected by the background insulin or basal. If your basal is insufficient then even a well calibrated insulin to carb ratio will not perform well. Once the basal insulin is set well then the meal-time rapid acting insulin has a chance to metabolically match the food eaten.
Keep in mind that morning is the time when many PWDs are impacted by "dawn phenomena," a higher need for background insulin, often the highest of the day. Very few PWDs are able to successfully dose for a bowl of cereal in the morning. For me, eating cereal has the same effect as eating the equivalent amount of carbs of table sugar. When you think about it, the cereal carbs are eaten with milk. It hardly slows down at all as it passes through the stomach and is then easily absorbed by the small intestine.
Many of us here have given up on cereal and pizza as foods that we can eat and still have post-meal BGs in range.
Waiting to eat for one hour after dosing is not just inconvenient but can also put you in danger of going low unless you remain vigilant. Interruptions in your routine, such as an unplanned visitor at the door, can completely distract you and delay eating.
I often delay eating my breakfast until I see a downward trend on my CGM.
To directly answer your question, rapid acting insulins like Novolog have an onset of about 15 minutes, a peak of 60-90 minutes, and a duration of action from 3-5 hours. These are all average numbers and your experience can differ and also vary from meal to meal for you.
That's where your mistake is -- thinking there will be no spike.
With the exception of no or very low carb meals, a diabetic will always be a rise. Simply put, it is impossible through subcutaneous administration to have insulin be able to change concentration in the bloodstream as fast as it does when it is dumped directly there by the pancreas.
However, with various strategies you can keep the overall profile after a meal pretty safe. Combination of pre-bolus timing, multiwave, and how/when you eat the carbs can really flatten this out.
I've been able to have an In-n-out Double Double for lunch (no fries) and go from 80 no higher than 130 then back to 80 again in about 3-4 hours by administering an impulse bolus for the carbs in the burger (39) plus another 15 carbs for a "followup snack" later. Then, I add to the program an extended bolus over 2.5 hours to cover the 50% of protein converted to glucose.
I have a CGM, set the low alarm at 100, then eat my other 15g (often 15 skittles) to head off the extra insulin taking me low.
All things being equal (i.e., no other variations, like a really active day or something), and this works nearly perfectly every time.
The extra insulin to cover the 15g carb later is, unfortunately, necessary for me to keep the initial carb load from spiking me up to 160-170. Many many people have, correctly, reminded me that staying up there for 1-2 hours before dropping back below 140 really isn't that big a deal, but I'm fanatical about this to some degree, and find the technical challenge stimulating and interesting. So, I develops strategies and tactics to try and stay as close to normal as possible.
Couldn't do it without a CGM and a pump. It's enough complication and attention-demanding with those tools to stay under 140 the vast majority of the time, and keep my fasting BG in the 80s.
The performance of any meal-time insulin is significantly affected by the background insulin or basal. If your basal is insufficient then even a well calibrated insulin to carb ratio will not perform well. Once the basal insulin is set well then the meal-time rapid acting insulin has a chance to metabolically match the food eaten.Hear hear!
Excellent point, and yet another subtlety that can and does affect T2's using bolus insulin as well as T1's. I just went through this myself in the last week.
I've been trying to get three days out of a Pod, but with an IC of 4, I've been a 2-dayer since I started. However, that was with a 1U/hr basal, the theory being take a load off my beta cells and let them recover some after my disaster with being out of control.
Last week, I decided to see if Mr. Pancreas could handle basal on his own. It's been an interesting, and partially successful experiment. The good news is, I now am getting 2.5 days out of a pod when I'm being a bit lax about carbs (150 in a day), and if I could discipline myself not to snack so badly before bed (stress), I could dial down my massive basal increase to 4U/hr from 3AM to 9AM.Even cutting that in half leaves me an additional 12U to cover carbs on day 3 (48g).
So, out of 200U, if I can drop things to 12U basal in the morning to cover DP, that leaves 164U for bolusing food and corrections. Sticking to about 150g a day, that would require 112U, leaving 52U for corrections and other variability.
All that said, what happened to my BG during all this? THAT was interesting. Seems my feeble beta cells can barely hold my BG steady between 100-130. Over that, and it slooooooooowwwwwwwwwwwwly comes down. Under that, and it creeps up.
That's T2 for you.
The rise below 100 is so slow that normal bolusing for meals targeting 85 ends up keep it down there most of the time (there's never enough time between meals for it to creep up 15-20 pts -- my rough calculation is that would take about 6 hours).
WHEW! Sorry for the really long post about this. The net-net is that I think I'm going to be successfull getting onto a 3-day stretch most of the time, with the 2-2.5 day spread now and then. I'm eager, 'cause I really want to build up a month or so of spare pods.
Maybe your basal is too low or you're not bolusing enough for higher carb meals or it is dp or a combo- just some thoughts. Novolog starts dropping me in 5-20 minutes but really peaks for me at 30-40 minutes depending on my bg at the time and other factors. I pre-bolus at 15-20 minutes but not if it is in the 80's or lower since that can cause a big hypo. Maybe you can figure out the timing or lower your carb content for meals, that can help too. Most pwd and others will spike though whatever the meal- I spike even with a protein fat meal- usually about 30-50 points.
A bowl of cornflakes with milk is about 50-75g of fast acting carbs and will metabolize into glucose faster than a bowl of table sugar. No brand of fast acting insulin will be effective unless you inject it way before, and getting it right is close to impossible. It's a volatile proposition that will either spike you or land you dangerously low. It's not the insulin, it's the corn flakes. I experimented with corn flakes and could never get it right. Try bacon and eggs as an alternative for breakfast. I inject 2.5 units right before eating and it keeps my levels completely flat. No spike at all.