Anyone who has insulin-dependent diabetes knows that managing it requires a lot of insulin injections.
Insulin injections are typically administered subcutaneously so that the medication can be quickly absorbed into the fatty tissue directly beneath the skin, but injecting insulin into muscle can be beneficial in some cases.
This article will go over the dos and don’ts of insulin injection into muscle.
How is insulin normally injected?
Insulin is typically injected subcutaneously, meaning into the layer of fatty tissue underneath the skin. This provides for a predictable release of the medication, more painless shots, and less injection site bruising overall.
Injecting insulin is now easier than ever thanks to super-small syringes and insulin infusion sets. When injected into fatty tissue, such as the stomach, arms, buttocks, or legs, most rapid-acting insulins begin working within 10-15 minutes and can remain in the body for up to 4 hours.
Why would someone inject insulin into a muscle?
Someone may accidentally inject insulin into a muscle, or they may not have a lot of fatty tissue on their body.
Sometimes people feel they’ve “run out” of injection sites and must inject into muscle, while other times they simply want their insulin to work faster.
Injecting into muscle can be more painful, so limit how frequently you do so. Injecting into muscle will also hasten insulin absorption, with the caveat that the insulin will be metabolised and out of your system faster as well.
Injecting into muscle can be beneficial if you are eating something high in added sugar (which will raise your blood sugar much faster) and need your insulin to kick in faster.
Is injecting into muscle safe?
While generally safe, you should be cautious of post-prandial (after meal) high blood sugars because the insulin will have a shorter tail on the backend.
Long-acting insulin should never be injected into muscle because the mechanism of action for longer-acting insulins will not function properly if not injected into fatty tissue. In general, injecting shorter-acting insulins (such as Humalog or Novolog) is safe. However, always consult your doctor first.
While it is not recommended to always inject insulin into muscle (it is subcutaneous for a reason), doing so in a pinch can be a good option.
What to do (and not do!) if injecting insulin into muscle
Do not inject long-acting insulin into muscle
Doing so can alter the effects of your long-acting insulin, wreaking havoc on blood sugars for 24 hours or more. Always inject long-acting insulin into fatty tissue.
Do not inject into muscle regularly
Injecting into muscle causes more bruising, is more painful, and insulin is not properly absorbed (it is absorbed, metabolised, and eliminated from the body much faster).
If you need your insulin to work better with the food you’re eating, try injecting 15-20 minutes before you begin eating and seeing if that helps.
Do try injecting into muscle if you have stubborn high blood sugar
Sometimes using this technique to get your blood sugars down faster is useful, especially when you’re sick and at risk for diabetic ketoacidosis (DKA).
Injecting into a muscle to lower your blood sugar faster before a big event, such as a school exam, movie night, or family dinner, can also help in a pinch.
Always talk with your doctor before doing so, though, and especially if you’re sick and experiencing chronic high blood sugars of over 250 mg/dL with moderate or high ketones for several hours.
In this case, you may need to seek emergency medical attention in the form of an IV insulin drip at a local hospital.
Do continue to use alcohol swabs and clean syringes
As always, to prevent infection, always use a fresh alcohol swab and clean syringe/pen when taking any injection. People with diabetes are at higher risk for infections in general, and this is an incredibly easy step towards preventing an unwanted hospital stay!
Do rotate your injection sites
Sometimes people with insulin-dependent diabetes simply feel as though they’ve “run out” of room for new injection sites. This is where injecting into a muscle occasionally can make sense.
Make sure you’re rotating your site appropriately, and not overusing any one area, as that can cause scar tissue and insulin resistance.
Do inject into a muscle if you’ve forgotten to bolus for a meal
Anyone can tell you that forgetting to bolus for carbohydrates consumed at a meal can be disastrous. Because injecting into a muscle causes your insulin to work much faster than injecting into fatty tissue, this method can be used if you’ve forgotten to dose.
Work with your doctor to see if this can be helpful for you.
Do carry extra low-snacks with you when injecting into a muscle
Because insulin acts much faster when injected into a muscle, keep plenty of low-carbohydrate snacks on hand if you’re on the go, as you may need to treat some unexpected hypoglycemia.
Keep a close eye on your blood sugar levels for several hours after injecting into a muscle, as the unpredictability of the mechanism of action may cause some blood sugar rollercoasters.
Do try inhalable insulin
If you frequently suffer from stubborn high blood sugars or regularly forget your meal bolus, ask your doctor about trying Afreeza, the inhalable insulin, which starts lowering blood sugar after only about 12 minutes.
This works much faster than some injections while hurting a lot less than taking a syringe to a muscle.
Always work with your doctor
Regardless of how you inject insulin, whether manually with multiple daily shots or via an insulin pump, you should consult with your doctor or endocrinologist to determine what is best for you and your lifestyle.
Knowing that you have the option of injecting into muscle on occasion can help you control stubborn high blood sugars, manage more difficult-to-dose-for meals, and prevent scar tissue in high-use areas for shots, but it does have drawbacks.
Injecting insulin into muscle alters how it is metabolised, can be painful, and may result in more bruising. Also, never inject long-acting insulin into muscle, as this can wreak havoc on your blood sugars and send you on a blood glucose rollercoaster for the next 24 hours.
With these strategies, you should be better prepared if and when you need to inject insulin into a muscle.
About Christine Fallabel
Christine Fallabel has been living with type 1 diabetes since 2000. She works in public policy, helping people with diabetes have better access to health insurance, affordable medication, and to fight disability-discrimination in the work and school environments. She earned her Master of Public Health from Temple University. In her spare time, she enjoys hiking with her husband in the mountains of Colorado, tinkering with her DIY Loop insulin pump, and vegan cooking.