About 6 million people in the United States use insulin, according to the American Diabetes Association. Meanwhile, the number of people using insulin in the United Kingdom has trebled between 1991 and 2010, according to research.
Insulin treatment is becoming more common for type 2 diabetes, while insulin treatment is fundamental for type 1 diabetes. With such a prevalence of insulin-dependent diabetes, the question “how much insulin should I take?” is an important one.
Types of Insulin Doses
To answer the question “how much insulin should I take?”, you need to know why you’re injecting insulin. You’ll be injecting different amounts depending on whether it’s basal or bolus insulin.
What is basal and bolus? We’ll tell you. But first let’s have a quick look at how insulin injections work.
Insulin injections are taken when your own body doesn’t produce enough insulin. You need that insulin because insulin is a fundamental part of metabolism.
Insulin makes sure that the sugar in your bloodstream (called blood sugar or blood glucose) can enter the cells to be used as energy.
Without that insulin, the sugar stays in your blood, and your blood sugar levels could get too high. So, when you eat or drink carbs, those carbs become sugar in the blood.
So, carbs will raise blood sugar levels. If you’re insulin-dependent, this means that you need to take insulin injections whenever you take carbs, to bring blood sugar levels down. This kind of insulin injection is called a bolus.
Rapid-acting insulin is most commonly used for the bolus – meaning you should usually inject between 5 and 15 minutes before eating or drinking carbs. This insulin remains active for 2-4 hours.
A part of the bolus dose includes the correction dose. This is because at some point, you might get high blood glucose/blood sugar either before eating or several hours after eating.
This can be caused by many different reasons, such as illness (like with diabetes and the flu), stress and diabetes, or even miscalculations. Either way, it’s not uncommon to have to deal with high blood sugar.
To bring the blood sugar levels down, you’ll need to inject insulin. This injection is referred to as the correction dose.
While you need insulin for particular moments of high blood sugar, the body will also need insulin that works in the background. This is to keep blood sugar levels stable throughout the day. Thus, an injection of long- or intermediate-acting insulin is taken usually once or twice a day. This injection is called the basal insulin.
Depending on the kind of insulin used, the intermediate-acting insulin remains active between 12 and 16 hours, while the long-acting insulin can remain active for 18 to 24 hours.
The answer, then, to “how much insulin should I take?” depends on whether you’re injecting for your bolus, correction dose, or basal dose. Read on to find out the answer!
Hedia’s job is precisely to make these insulin calculations easier. Find out how Hedia takes the mathematical formulas and turns them into insulin recommendations: download Hedia from Google Play or the App Store!
How much Insulin should I take? :Bolus
The amount of insulin needed for the bolus depends on how many carbs you’re going to have. You need to know how many units of insulin will cover a certain amount of carbs. This is called the insulin-to-carb ratio.
For instance, one unit of rapid-acting insulin might cover 10 grams of carbs. Your ratio would then be written as 1:10. Accordingly, if you ate 10 grams of carbs, you would need to inject 1 unit of insulin.
The insulin-to-carb ratio varies for each person; speak to your healthcare team to get help with figuring out your ratio.
Your ratio will often be established through trial-and-error. However, a standard formula for the ratio is the 500 rule.
This is where 500 is divided by your total daily dose. Your total daily dose is the amount of insulin for your bolus and basal doses combined per day (under the section for how much insulin to inject for basal doses, you’ll find a general formula to figure out your total daily dose).
Thus: 500 ÷ total daily dose = the number of grams of carbs covered by 1 unit of rapid-acting insulin.
If your total daily dose was 50, this would give you the following calculation: 500 ÷ 50 = 10. This would mean that 10 grams of carbs would require 1 unit of insulin, giving you the ratio of 1:10.
How much Insulin should I take?: Correction
If your blood sugar is too high during a period of fasting (by which we mean a period during the day before your meal), you can calculate how much of the blood sugar needs to be lowered.
To figure this out, you’ll need to know your correction factor, also known as the insulin sensitivity factor.
The correction factor is the amount of blood sugar that will be lowered by 1 unit of rapid-acting insulin.
This should also be figured out together with your healthcare team, using trial-and-error. Meanwhile, a helpful standard formula is the 100 rule or the 1800 rule.
Blood sugar is measured in either mmol/L or mg/dL. The 100 rule is for people who use mmol/L, while the 1800 rule is for those who use mg/dL.
These “rules” are formulas that involve dividing 100 or 1800 by your total daily dose. Thus: 100 ÷ total daily dose = the number of mmol/L of blood sugar dropped by 1 unit of rapid-acting insulin.
Alternatively: 1800 ÷ total daily dose = the number of mg/dL of blood sugar dropped by 1 unit of rapid-acting insulin.
Let’s say again that your total daily dose is 50, giving you the following calculation: 100 ÷ 50 = 2. This means that 1 unit of insulin lowers 2 mmol/L of blood sugar.
Alternatively, the example could be the following calculation: 1800 ÷ 50 = 36. Accordingly, 1 unit of insulin lowers 36 mg/dL of blood sugar.
How much Insulin Should I take?: Basal
For your basal dose, you’ll usually inject a set amount of insulin each day. The Diabetes Education and Research Center (DERC) gives a formula for a general idea of how many units are needed.
The DERC first suggests calculating your total daily dose (also known as the total daily insulin), which is the amount of insulin for your bolus and basal doses combined per day. This is calculated by dividing your weight in pounds by 4.
Then, the DERC proposes that the basal dose should be half of the total daily dose. Thus: total daily dose ÷ 2 = basal dose.
However, this is only a proposed general guideline. For a personal idea of your basal dose, you should be advised by your healthcare team, who will take other factors into account, such as the kind of insulin you’re using.
Do I need to do the Math Every time?
Phew! Good to get those calculations out of the way!
But are they really out of the way if you need to inject insulin every day? Well, they can be out of the way with the help of Hedia’s insulin calculator.
Hedia takes the numbers for your insulin-to-carb ratio and your correction factor – or uses the 500 rule and the 100/1800 rule – and does the maths for you!
All you need to do is first tell Hedia your blood sugar level, which can be added wirelessly with certain blood glucose monitors. Then, add if you’re having any carbs – you can use Hedia’s food database to help.
Finally, tell Hedia if you’re exercising (since exercise can affect blood sugar too) and whether you’ve injected insulin recently.
That’s it! Hedia can now give you a personal recommendation for your insulin dosage. No formulas to fiddle with – just a tap of a screen.
Insulin Amounts made easy
Most people with diabetes will probably say that calculating your insulin is no walk in the park – so much so that we have a blog post dedicated to 11 things that are as hard as calculating your insulin dosage.
With more people using insulin nowadays, it’s important to get help with calculating that important but tricky insulin dosage.
We hope that these formulas will have given you a general idea of how insulin is calculated, and help you in the process of determining your own dosage. We also hope that Hedia will turn the bore of those calculations into more free time for you!