Long acting insulins have been around for a while now but in the grand scheme of things, they are still relatively new to the diabetes world. Over the years they have been redeveloped and improved.
Long acting insulins are used in the treatment of types of diabetes. Most commonly they are used in type 1, type 2 and type 3c diabetes.
There are many types and brands. Lots of different pharmaceutical companies make their own versions. Each having a slightly different effect on and duration in the body.
All long acting insulins are analogue insulins. These replaced older insulins known as human insulin. This change made insulin more predictable and stable, though human insulins are still used.
This article is to explain everything you need to know about long acting insulins so you can become the expert.
What are Long Acting Insulins
Long acting insulins are a type of insulin that are injected once or twice a day. Whether injecting once or twice depends on the type of insulin and your individual circumstances.
There are many brands but the most common are Lantus, Levemir, Abasaglar, Tresiba and Toujeo. Over the years more long acting insulins have come to market and we are now a bit spoiled for choice.
These can be grouped into categories based on how they are made and act in the body. Glargine (Lantus, Abasaglar & Toujeo) and Determir (Levemir) are the two most common groups. However, Tresiba’s entry to market has opened a new category called Degludec.
Long acting insulins are also called basal insulins or background insulins. These terms are used interchangeably so try not to get confused if your medical team switches between the terminology.
We can use the names of the insulin to get an idea of the type of insulin it might be. Remember, Lantus and Levemir start with an ‘L’ for long acting. No other type of insulin starts with an ‘L’. Abasaglar seems like an odd name but look closer – ‘A -Basal-Glargine’. Granted Tresiba and Toujeo aren’t so obvious, so you just have to remember those ones.
How do they work
Long acting insulins prevent your liver from releasing too much glucose. Without diabetes your liver releases just the right amount of glucose throughout the day but in diabetes it gets a bit confused. This is because insulin is either not present or not working very well in the body. This will depend on your type of diabetes.
As a result, the Liver releases more glucose than it normally would causing high glucose levels. Long acting insulins prevent this happening and tell the liver to release glucose at a slower rate.
Long acting insulins stay in your body between 18-36 hours depending on the brand. Originally, it was thought all of the brands lasted at least 24 hours. However, since those earlier days, we have found certain insulins like Lantus (20-24 hours) and Levemir (18-24 hours) might not quite give you full coverage over the day.
Sometimes you will also need to take short or rapid acting insulin alongside your long acting insulin. This is called a basal bolus insulin regimen. This is most commonly used in type 1 diabetes but is also used in other types of diabetes. The idea is your long acting insulin looks after the liver. Meanwhile, your short or rapid acting insulin deals with glucose entering your blood after meals.
Before long acting insulins were released to market, we relied upon intermediate acting insulins. Intermediate acting insulins provide shorter insulin coverage throughout the day and therefore are usually given twice a day.
Besides the duration of each insulins action, we also look at an insulins peak. An insulins peak describes how much of that insulin is initially released before levelling out. Using an insulin with a high peak means you get more insulin into your system during that peak. So if you were to plot it out onto a graph you should literally see a peak in the graph.
As you can see, long acting insulins such as Lantus have a very subtle peak but are mostly flat. The newer long acting insulins such as Tresiba and Toujeo have an even flatter profile. Whereas, the older intermediate acting insulins had a large peak upon administration and gradually tailed off as the day went on.
How are long acting insulins administered
All insulins are given by an injection. An insulin injection is different from the types of injections you might be thinking of though. Insulin needles are very thin. In fact, they are smaller than a hair follicle. Over the years these needles have become smaller and smaller and now are only 4mm long. If you’re using a longer needle than this, it might be worth speaking with your medical team.
If you need more information on injecting here’s a guide to how to do it or watch this YouTube video.
How many times a day do I take it
Due to the fact long acting insulins last between 18-36 hours, you only need to take them once or twice a day. Mostly they will only be a once daily injection. This can be given whenever best suits you but it should be around the same time each day.
The newer, longer acting insulins that last up to 36 hours still need to be taken every day. Interestingly these insulins do not accumulate in your system. An ingenious release mechanism stops the insulin entering your system all at once and gradually drips into your system.
The best analogy I can offer is thinking of longer acting insulins like a group parachute jump. You can put more jumpers in the plane (type of insulin) but they still only jump out one at time (insulin release into the body). So the jumpers will leave the plane at the same rate as the other insulins but ultimately, people will be jumping for longer. So they are longer acting.
How much insulin do I need
Insulin is measured in something called ‘units’ This isn’t like your alcohol units. This is different. The dose needed will depend on each individual. You will need what you need and so there are no right and wrongs here.
Dialling your dose is easy and your medical team will be able to advise you on this. Each insulin pen has a dial on the end of the pen. Simply dial up your dose and inject the insulin. See the link above for further advice on how to do this.
How often do I need to test my blood glucose levels
This is slightly tricky because it depends. If you’re following a basal bolus regimen as explained above, ideally you’ll test your glucose levels before each meal and before bed as a minimum.
If you are only using long acting insulin you can get a bit more flexible. Initially, I’d encourage you to check your glucose levels throughout the day to understand what is happening. We’ll talk a bit more about how to understand if your long acting insulin dose is correct shortly. However, once you’re satisfied your dose is working for you and it isn’t causing high or low glucose levels, most patients will test once a day upon waking up.
How do I know if my dose is correct
There are a couple of techniques to understand whether your dose is correct. The first method is looking at the difference between your pre bed glucose level and your waking glucose level. If you go to bed with a glucose level in target range and wake with a high glucose level, it shows something is off. It is more than likely your dose is insufficient. Just be cautious in this instance though because high waking glucose levels can also be caused by overnight hypos. Your liver releases glucose when your glucose levels go low. So it’s always good practice to check your glucose overnight a few times to rule out this being the cause before increasing your dose.
Alternatively, if you go to bed with a high glucose level but wake with a low glucose level it likely means your dose is too much.
However, if you prefer to test this when you’re awake, there is a way. Carbohydrates are the food that most effect your glucose levels. Exercise and additional insulins will also effect your glucose levels. Usually, short or rapid insulins are only there to compensate for any carbohydrates you eat so here’s what you can do.
Perform a basal test. Choose a day when you’re not going to be physically active. Then over the course of a few days eat some carbohydrate free meals. So just eat protein foods, vegetables and salad. An omelette or chicken salad are good examples of how to do this.
You can vary breakfast, lunch and dinner sometimes opting to test 2 meals in the same day. If you take rapid or short acting insulin, withhold this insulin at the meals you do not eat carbohydrates.
Then test your glucose levels before each meal and see what happens. If your glucose levels start to rise or drop significantly despite doing no exercise, no carbs or taking any other insulin, it shows your background insulin might be off.
To help this, we tend to suggest increasing your dose by 10% increments for high glucose readings. If low glucose levels are the problem, we suggest reducing your dose by 10-20%. If you over shoot the reduction you can always increase this later.
How often should I adjust my dose
In healthcare we encourage patients to own their insulin management. Assuming they feel comfortable with this of course. It’s no use waiting around for your diabetes to tell you to adjust your insulin to deal with obviously high or low readings. You can do this. However, there are some considerations.
Insulins like Lantus, Abasaglar and Levemir take a couple a couple of days to level out so give them some time. Longer acting insulins like Tresiba and Toujeo take 3 days to reach a steady state in your body. Therefore, only increase these insulins every 2-3 days depending on your type.
If you’re experiencing hypo’s you can reduce the dose more often (as the worry is continually increasing your dose before they have levelled out may cause hypos). However, keep in mind, you may not see the effect of your dose reduction for up to 3 days anyway. In this instance, it might be worth reducing your dose but in the subsequent 3 days make sure you have a solid supply of carbohydrates available to prevent hypos.
Benefits of long acting insulin
One of the best benefits of most of them is they give you 24 hour insulin coverage. This usually means only having to inject once a day for your background insulin.
They also have small or no peaks. This reduces the risk of hypo’s because there isn’t a surge of insulin release at any given time. Obviously, you will get more variability with your glucose levels if there are lots of peaks and surges of insulin after injecting. Reducing peaks therefore reduces the variability.
The newer brands of insulin such as Tresiba are also seeing additional benefits. It seems Tresiba provides the same benefits in terms of glucose lowering capabilities as its counterparts whilst reducing the occurrence of hypo’s. This is due to its flatter profile. This means less glucose variability for the insulin user.
Negatives of long acting insulin
Wherever there is a pro there is a con and long acting insulins are no different. With any insulin there is always a risk of hypo’s. Therefore, testing your glucose levels regularly helps to understand your blood glucose response.
Insulin is also an anabolic hormone and thus encourages your body to store nutrients like fat and glucose. In other words, insulin makes you put on weight. The average weight gain isn’t tremendous, perhaps a couple of kilograms. However, if you’re already struggling to lose a few pounds, this can make it difficult.
As long acting insulins only work in the background they may not provide enough insulin coverage to compensate for food. Sometimes just long acting insulins will be enough to prevent high glucose levels and your pancreas will do the rest with food. It all depends on the type of diabetes you have and how far it has progressed.
However, if you’re struggling to control your glucose after eating it might be a sign you need additional rapid acting insulin. Unfortunately, just increasing you long acting insulin will rarely help deal with high glucose levels from food and can leave you at risk of overnight hypo’s.
You can reduce your carbohydrate intake to prevent big rises in your glucose levels after meals. Protein, vegetables and fats do not have the same glycaemic effect on your glucose levels as carbohydrates. I wouldn’t suggest going completely cold turkey on the carbs but minimising the amount you eat and/or relying on vegetables, fruits, beans, pulses and lentils to provide your carbohydrate intake could be a good way of steadying your glucose levels.