Sliding scale or Insulin to Carbs Ratio-Which is better for you?

Hello everyone:

I am wondering how many of you out there are on a sliding scale? I was just placed on Novolog insulin along with my basal insulin Levemir. Or how many of you just do the insulin to carbs ratio? I am very interested to find out.

The sliding scale is not always best since my blood sugar isn’t always high before the meals I eat, but spikes afterwards. I have found out that by adding up my total carbohydrates per meal and injecting one unit of Novolog for every 15 carbs works the best, and then I don’t have the 180-250 spikes.

Write back and let me know which method you prefer for injecting your fast-acting insulin.

Waiting to hear!


You can do both. First figure out (with your doctor or cde) how much insulin you need per gram or carbohydrate. I need one unit for every 13 grams or carbs. so that is 1:13. Next you need to figure out what your correction does would be. Mine is 1:25, 1 unit of insulin for every 25 mg/dL I am over 100. So lets say I am 125 before a meal and I am eating 39 grams of carbs. I would take 1 unit for by BG and 3 units for my food so 4 units in total. It also works in reverse. say I was 75 instead of 125 i would subtract a unit from my food so for that meal I would only take 2 units (and I might wait 15 minutes since I was a bit on the low side before bolulsing). Now keep in mind Novolog in may people has a 4 hour life plus a tail, so give ti time or you will stack your insulin and might go low.

“(bg-100)/s” + (C/r) = insulin

bg is your blood glucose
s is your sliding scale ratio
C is you carbohydrate in your meal
r is your insulin to carbohydrate ratio

I had to learn how to do this before I could get an insulin pump. Wish I had been told this when I was first diagnossed.

So here is the math for the first example.

“(125-100)/25” + (39/13)= 4units
the second example
"(75-100)/25" + (39/13)= 2 units

All it take is a note pad and if you are like me a small calculator and you can be very precise in your dosing.

I do both, but my ratio is 1:12 my correction factor is 1:15 for anything over 120. This is the way that my endo started me since my diagnosis a little over two months ago.


No one should be using the outdated sliding scale method for the very reason you mentioned. Matching insulin to carbs is the best & most accurate way. Good for you for figuring this out on your own! Don’t know why doctors don’t have people carb count right away, but many begin on a sliding scale. Makes no sense not to do this correctly from the beginning.

FYI–ratios can change & many people have different insulin:carb ratios for breakfast,lunch & dinner. If you change doses, do it slowly by 1 unit at a time & keep the same ratio for three consecutive days (or longer).

My doc told me to take Humolog 3 units plus 1:10 unit/carb ratio per meal. I also take 60 units Lantus divided into 30 units doses twice a day. It works well for me,
I have to do 1:5 ratio if I even look at a piece of bread.
I am a T2 so that may make a difference.

Correction doses for highs require a ratio also.

All my doc said was if my fasting was close to 200 to raise my dose to 5 units plus sliding scale. I am learning all this still. I know the Humolog levels out in me at 4 hours. By then I am in the 85-95 range. I have not given myself any correction dose because I don’t want to bottom out at 4 hours. I am open for advice and help. I know I am not the same as everyone else, but any advice can give me guidance. thanks so much!


What your doctor suggests isn’t precise. In addition to knowing how much extra to take with meals, you also need to know how to correct highs without a meal bolus. Four hours is too long to have a high when you can lower it sooner & not have a high to begin with with proper doses.

Your basal rate (Lantus or Levemir) may be too high because you’re going down to a good number in 4 hours, so it may not be the Humolog doing the job. Or, you may have to change the timing of your meal insulin. Nope, you don’t want lows. Do you take Humolog with meals, before meals? Timing of insulin to digestion is important.

Humolog usually stays in the body for about 4 hours.

Please ask your doctor to teach you to count carbs & help you figure out your insulin:carb ratio.

I usually take Humolog with meals. I work as a floor nurse. I cannot take my insulin and wait 15-30 minutes to eat. I may not get another chance to eat.
When I am at home, I take the Humolog while preparing a meal. If I am able to do so, I do not go up more than 30-40 points 2 hours post prandial, unless I eat a slice of bread or any starchy carb.

I never thought about the Lantus being too high. I was started on it when the Januvia/Metformin was not doing the trick. When I got to the 60 units of Lantus, I told my doc that I needed a mealtime insulin. I am now on Metformin and the Januvia was dropped.

I appreciate all the direction I can get. Being a nurse does NOT make me an expert even though many folks think that working in that profession makes you a know all medical answers.

I know I am unique and what works for one may not for another. Please send all ideas and advice my way. I REALLY do appreciate it.


That’s got to be one of the toughest jobs.

When you can, start by taking insulin 15 minutes before meals. That’s the usual recommendation. Timing insulin to food is critical. Only going up 30-40 pts is great. Am hoping that you’re started out before meals with good BG. What my endo had me do at first was testing at 1 hour, 2 hours & 3 hours after meals for a week to see where the rise started. From there, I changed timing of insulin. By logging this you’ll have records to show your doctor to fine tune. This & learning your ratios will give you better control. Forget that sliding scale stuff. This puts BG all over the place.

Good for you for telling your doc you needed rapid acting for meals!

The way to test Lantus is to not eat for 5-6 hours & keep testing on a day when you’re not too active, hormonal or stressed. If your BG stays level during this period, you’ve got the correct dose.

Don’t let your doc tell you that Lantus lasts 24 hours because for many people it doesn’t. I have better results by switching to Levemir. Lantus had peaks for me that caused lows.

Hope this helps.

This is great everyone! Keep the comments and advice for me coming. I even printed out these answers to study so I can learn.



Thanks for the advice. Like Jennifer says, keep it coming!

Gerri. I usually will have a fasting bg of 100-130 before meals. Maybe on a weekend off I can try the timing with the Lantus. As soon as I can I will try the 1,2,3 hour after meal trials.
I appreciate all answers. I LOVE my TuDiabetes family knowing we are all in this together.

Keep us posted!

I have found a sliding scale that works for me. It may not work for anyone else, but it works for me. I take novalog and lantus. Here is the formula: (current BG level - target BG level)/ 4 = units of novalog and units of lantus.

Technically, you are using an insulin to carb ratio, not a sliding scale. When you use an insulin to carb ratio, you subtract your current BG from your target BG and then divide the difference by the amount one unit of insulin lowers your BG. (For you, that number seems to be one unit of insulin lowers your BG by 4 mg/dl or 4 mmol/L, depending on which units you’re using.)

A sliding scale is when yuo are given a fixed amount of insulin to take based on BG level. Lots of people are told to take no extra insulin if their blood sugar is below (say) 150 mg/dl, 1 unit extra if their blood sugar is between 150-200 mg/dl, 2 extra units if thier blood sugar is between 200-250 mg/dl, and so on. When I was a kid and up until I switched to Lantus in 2005, the type of sliding scale we used was just to give an extra unit for every 2 mmol/L my blood sugar was above 8 mmol/L. So if I was 10 mmol/L, I’d take 1 extra unit, if I was 12 I’d take 2 extra units, and so on.

Thanks. I knew it worked, but I didn’t understand why it worked.:blush: