Medically reviewed guide · Last updated: 23 June 2026 · Reading time: approx. 13 min

Injecting insulin correctly: step by step

Anyone who has to inject insulin learns the technique at the start of the therapy in a diabetes training. In everyday life, however, routine quickly sets in, and over time small mistakes often creep in that were only addressed verbally in the training. Yet the correct injection technique decisively determines the therapy success: studies show that a large part of difficult-to-adjust insulin therapies goes back to a faulty technique. This guide leads step by step through the injection, explains the injection sites and the rotation scheme and shows how the most frequent mistake, the lipohypertrophy, can be avoided. Important beforehand: this guide does not replace a diabetes training and no medical advice and deliberately contains no dosage details. Its aim is to make what is often only conveyed verbally readable in writing and at leisure, so that small mistakes do not creep in at all.

At a glance

  • Insulin belongs in the subcutaneous fatty tissue, not in the muscle and not too flat in the skin.
  • With short needles of four to five millimetres, one mostly injects vertically at a 90-degree angle.
  • After pressing, the needle stays in the skin for about ten more seconds.
  • The consistent changing of the injection site is the most important protection against lipohypertrophies.
  • Dosage and therapy plan are always determined by the diabetes team, never by this guide.

Why the technique is so important

Insulin is a hormone that lowers the blood sugar by enabling the body cells to take up sugar from the blood. With diabetes the pancreas produces no or too little insulin, or the body cannot properly utilise the existing insulin, so that it must be supplied from outside. So that it works correctly, it must get into the subcutaneous fatty tissue, the layer between skin and muscle. There small blood vessels take up the insulin evenly. If it is accidentally injected into the muscle, it floods in too quickly and can lead to blood sugar fluctuations. If it is given too flat into the skin, it gets into the blood worse and works unreliably. Exactly for this reason, needle length, angle and injection site are no trivialities but decisive for a stable blood sugar adjustment. Even small deviations in the technique can directly affect the values and make an otherwise well-planned therapy waver.

Added to this is the place of the injection. Insulin is taken up at different speeds depending on the site: from the belly it gets into the blood faster, from thigh and buttocks slower. This property is used therapeutically, which is why the diabetes team determines which preparation belongs at which site. Thus for example fast-acting meal insulin is often assigned differently than slow-acting basal insulin, but the concrete assignment is always individual. Important is that this assignment is discussed individually and does not apply across the board. This guide explains the general technique but deliberately makes no statements about amounts, timing or the assignment of individual preparations, because that is part of the personal therapy plan. These determinations are different from person to person and depend on diabetes type, lifestyle and many further factors.

This guide does not replace a training

The first instruction for injecting insulin belongs in a structured diabetes training, in which the technique is shown, practised and checked. There a lot can be clarified that is difficult to convey from a text alone, for example the right feeling for the skin fold or the fitting injection angle. This guide is aimed at people who already have an insulin therapy and helps to refresh what was learned and to recognise typical mistakes. It contains no dosage details and no instruction for dose adjustment, since these are determined exclusively medically. If you are unsure, were never shown the technique correctly or notice new complaints, turn to your diabetes team or your medical practice. Relatives too who support with the injecting should have the technique shown to them professionally once, so that all involved proceed safely and uniformly.

Step by step through the injection

Even if the handling differs slightly depending on the pen model, the injection follows a clear sequence. It is worth going through this sequence once at leisure and making the individual steps conscious before they become second nature. For the preparation you first wash the hands thoroughly with soap and warm water. With clean, intact skin a disinfection is as a rule not necessary in everyday life, but the injection site should be clean and dry. Afterwards you check the insulin for shelf life and appearance, put on a fresh needle and vent the pen according to the instructions, in order to ensure that the needle is free and ready for use. Only then is the dose determined by the diabetes team set, whose concrete amount is part of your personal therapy plan. Some pens release the dose audibly in steps, which eases the setting also with limited eyesight, others have larger displays or half units, about which your diabetes team advises you.

For the actual injection you choose a suitable site in the agreed area and keep distance to the last injection site. The skin at this site should be healthy, that is free of wounds, rednesses or hardenings, and you should sit or stand relaxed, so that the musculature is loose. With the short needles usual today, one as a rule pricks vertically at a 90-degree angle swiftly. A swift, decisive pricking is mostly felt as more pleasant than a slow, hesitant approach that stretches the skin unnecessarily. With very slim people, with children or when injecting into the thigh, a skin fold lifted loosely with thumb and index finger can be sensible, in order not to get into the muscle. Then you press the dosing button slowly and completely through and leave the needle in the skin for about ten more seconds before you pull it out. A skin fold is only released again afterwards. After injecting you unscrew the needle and dispose of it safely, because this way neither air can get into the cartridge nor insulin escape.

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Injection sites and the rotation scheme

The probably most important habit with injecting insulin is the consistent changing of the injection site. Anyone who injects again and again into the same site risks changes in the subcutaneous fatty tissue. This often happens unconsciously, because a familiar site is less sensitive and the injecting goes more easily there, but exactly this convenience is risky in the long term. A proven approach is a fixed rotation scheme: one divides for example the belly mentally into four quadrants around the navel and changes according to a fixed rhythm, for example weekly clockwise, from quadrant to quadrant, so that no site is used too frequently. Alternatively one injects in rows and moves a bit further with each injection. Important is to always keep at least two finger widths distance to the last injection site and to the navel. It has also proven useful to use one side of the body for a week and then change to the other, so that the tissue of the first side can recover at leisure.

A pitfall of the routine is that many change between the right and left side of the body and believe to rotate sufficiently with this, but in truth hit the same small areas again and again. Here a conscious, documented scheme helps, for example an injection calendar, as professional societies too recommend. Especially at the beginning it can help to circle the injection sites with a pen or to note the used areas. Equally useful is an app or a small diary in which you record where you last injected, so that you keep the overview also when out and about. This way you give each area enough time to recover and ensure that the insulin is taken up evenly everywhere. This may sound laborious at first but quickly becomes a habit and pays off through more stable blood sugar values and an often lower insulin need.

Body site Particularity
Belly faster uptake, much subcutaneous fatty tissue
Thigh slower uptake, skin fold often sensible
Buttocks slower uptake, well suited for rotation
Lipohypertrophy never inject into it, let it heal first

Lipohypertrophies: the most frequent mistake

Lipohypertrophies, colloquially injection lumps, are benign hardenings of the subcutaneous fatty tissue that arise through repeated injecting into the same site. They are frequent and treacherous, because the insulin is taken up from them unevenly, which can lead to fluctuating blood sugar values and unexplained low blood sugars. Since they are often less sensitive to pain, it is tempting to inject again and again into them, through which they grow further. Never inject into known hardenings and have your injection sites palpated and checked regularly, for example every three to six months, in the medical practice or by the diabetes team. Treacherous is that an inexplicably fluctuating blood sugar adjustment often only clears up through the palpating of the injection sites, which is why this simple step should belong to it regularly.

Frequent mistakes and how you avoid them

Besides the missing change of site there are some further typical stumbling blocks. Many of them arise not out of ignorance but out of routine and time pressure in everyday life, which is why it helps to consciously call them to mind again from time to time. A widespread mistake is the multiple use of pen needles: they become blunter with each use, irritate the tissue more strongly and can make the injecting more painful, which is why they should be changed after each injection. Equally important is to unscrew the needle directly after injecting, so that no air gets into the cartridge and no insulin escapes. The too early pulling out of the needle too is a classic mistake, because then a part of the insulin can flow back. The ten seconds of waiting time are worthwhile. A further frequent point is the storage: opened insulin is mostly kept at room temperature, supplies belong in the fridge but not next to the freezer compartment, and strongly heated or frozen insulin should no longer be used.

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In sum it applies: the correct injection technique is learnable and becomes with some practice a safe routine. Decisive are the injecting into the subcutaneous fatty tissue, the fitting angle, the consistent changing of the injection site according to a fixed scheme and the conscious handling of needles. Anyone who observes these basic rules effectively prevents the most frequent mistake, the lipohypertrophy, and ensures an even insulin uptake. It is worth questioning one's own technique occasionally even after years of routine and having it checked in the diabetes team, because precisely ingrained habits otherwise often remain unnoticed. Insulin is used both with type 1 diabetes and with many people with type 2 diabetes. Since insulin is prescription only, dosage and therapy plan always belong in medical hands and in the diabetes training.

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Frequently asked questions about injecting insulin

Insulin is injected into the subcutaneous fatty tissue between skin and muscle, above all into belly, thigh or buttocks. It must not get into the muscle and not too flat into the skin. From the sites it is taken up at different speeds, which is why the diabetes team determines which preparation belongs where. Which sites are suitable for you, you learn in the diabetes training.
With the short needles usual today of four to five millimetres, one as a rule pricks vertically at a 90-degree angle swiftly. With very slim people, with children or at the thigh, a skin fold can be sensible, in order not to inject into the muscle. This is lifted loosely with thumb and index finger. Whether a skin fold is necessary, you clarify with your diabetes team.
Anyone who always injects into the same site risks lipohypertrophies, that is hardenings of the subcutaneous fatty tissue, from which insulin is taken up unevenly. This can lead to fluctuating blood sugar values and increased insulin need. A fixed rotation scheme distributes the injections and gives the tissue time to recover. Keep at least two finger widths distance to the last site and to the navel.
A lipohypertrophy, colloquially injection lump, is a benign growth of the subcutaneous fatty tissue through repeated injecting into the same site. At first rather palpable as a rubbery hardening, later as a visible lump. It is frequent and problematic, because insulin gets from it unevenly into the blood. Since it is less sensitive to pain, it is often injected into, which lets it grow further.
The most important protection is a consistent rotation scheme, for example over four quadrants on the belly or in rows with a fixed distance, at least two finger widths to the last site and to the navel. Use pen needles only once and do not inject into existing hardenings until they have receded. Have your injection sites checked every three to six months medically or by the diabetes team.
With clean, intact skin a disinfection is as a rule not necessary in everyday life. Thorough hand washing with soap and warm water mostly suffices, the injection site should be clean and dry. In care, in the hospital or with a weakened immune system, other rules can apply. The skin should be healthy, without wounds or hardenings. What applies with you, you clarify with the diabetes team.
After the complete pressing of the dosing button, the needle should stay in the skin for at least about ten more seconds, so that no insulin flows back and the dose is completely delivered. A skin fold is only released after the pulling out. The exact handling can deviate depending on the pen model, which is why the instructions and the training are decisive.
Pen needles are intended for single use and should be changed after each injection. With each use they become blunter, irritate the tissue more strongly and increase the risk of lipohypertrophies. Unscrew the needle directly after injecting, so that no air gets into the cartridge and no insulin escapes. Fresh, thin needles make the injection almost pain-free.
Yes. Insulin is prescription only and available only after medical diagnosis. The therapy is determined and accompanied medically, mostly by a diabetological practice or a diabetes team, including preparation choice, therapy plan and individual dosage. This guide explains only the injection technique. Dosage and therapy decisions belong exclusively in medical hands and must not be changed on one's own.

Related topics

Sources

  • diabinfo.de (German diabetes information service): injection sites, uptake speed, skin fold, needle length, change of site
  • Apotheken Umschau: six steps of the pen injection, ten seconds waiting time, use needle only once, skin fold
  • AOK health magazine: rotation scheme, four quadrants on the belly, marking the injection sites, lipohypertrophy prevention
  • German Diabetes Society and professional sources: injection calendar, faulty injection technique as a frequent cause of fluctuating values
  • mgo medizin and Accu-Chek guide: 90-degree angle, four to five millimetre needles, disinfection with intact skin, mixed insulin
  • Ärztezeitung: lipohypertrophies and unexplained low blood sugars, distance and needle change for prevention

This guide serves general, neutral information about the injection technique and does not replace a diabetes training, no medical advice, diagnosis or treatment. It deliberately contains no dosage details and no instruction for dose adjustment. Insulin is prescription only, the insulin therapy is determined and accompanied medically, mostly by a diabetes team. Dosage, preparation choice and therapy changes belong exclusively in medical hands and must not be changed on one's own. The first instruction for injecting belongs in a structured training. With uncertainty, new complaints or hardenings at the injection sites, turn to your diabetes team. With signs of a severe low blood sugar with disturbance of consciousness, call the emergency number 112.