Put Some Muscle in Your Insulin
by gary scheiner, MS, CDE
Faster than a speeding bullet. More powerful than a locomotive. Able to overcome high blood sugar with a single bolus. It’s…well, you know the rest.
Insulin can do a lot of things, but I would never compare it to a “speeding bullet.” The fact is, even our so-called rapid-acting insulin analogs pale in comparison when it comes to the insulin produced by a functioning pancreas. Endogenous (naturally produced) insulin begins working seconds, not minutes, after it is secreted. Because of the location of the pancreas, endogenous insulin absorbs first into the liver circulation, where it has its greatest immediate impact, then travels through the bloodstream to the muscles and other organs. Its “peak” is in a couple of minutes, and it is cleared from the bloodstream a few minutes later. Now that’s rapid. Compare that to “rapid-acting” insulins (Novolog, Humalog, Apidra), which take several minutes to start working, peak in 45 minutes to two hours, and take anywhere from 3-6 hours to completely finish working. Rapid? Hardly. Sure, it’s more rapid than Regular, but that doesn’t sell all that well from a marketing standpoint.
Why is faster better? I can summarize that in one word: MANEUVERABILTY. Injecting (or pumping) “rapid” insulin is like a home thermostat that takes forever to respond to temperature changes. Your home might be freezing cold before the heat kicks in, or swelteringly hot before the air turns on. Naturally-produced insulin is like a very sensitive thermostat that responds almost immediately to the slightest change in temperature, keeping things comfy all the time.
When insulin takes too long to react to blood sugar changes, bad things happen. Any increase in physical activity can cause blood sugar to drop too low. Even if insulin delivery stops completely at the first sign of exercise, any insulin that was given in the previous several hours is still working. As mentioned above, it takes at least three hours for rapid insulin to fully “clear” from the body. And factors that raise blood sugar quickly – such as stress and the vast majority of carbohydrates we consume – will kick in long before rapid insulin has a chance to peak. This, of course, results in the post-meal blood sugar spikes that most of us have become accustomed to.
So why don’t we just make rapid insulin more rapid? An important challenge is the site of administration. Anything given into the fatty layer below the skin (subcutaneously) must diffuse through the fat just to reach the bloodstream. Once in the bloodstream, it can then be distributed to glucose-hungry cells throughout the body. All this takes time.
Several companies have been working on techniques for accelerating the action of insulin. Strategies have included chemical additives that help propel the insulin molecules through the fatty layer; changing the structure of the insulin molecule to speed their rate of diffusion; delivering insulin directly into bodily compartments other than the subcutaneous fat; breaking the delivery down into smaller parts so as to enhance the absorption rate; and heating the infusion site to increase blood flow. These approaches are actively in development, although none are currently available to people with diabetes.
So what’s a person to do? Just accept that you have a faulty thermostat and deal with it? Well, you don’t have to. There are a number of down-home grassroots ways to make your insulin work faster. Listed below are just a few of these. Please note that these approaches may work differently for different patients. To determine how they affect you, I suggest frequently checking your blood sugar whenever you try using these tips. Also, for those with younger children with diabetes, these strategies may drop blood sugar more quickly than in adults. I encourage you to speak with your healthcare provider before making any changes, especially in these younger patients.
1. Put some insulin in your muscle.
No, it’s not a dyslexic typo. Injecting insulin into muscle makes it work faster. Much faster. From my experience analyzing data from continuous glucose monitors, insulin injected into muscle peaks and finishes working twice as fast as insulin injected into the fatty later below the skin. It doesn’t work harder, just faster. Good sites to inject include the forearm, triceps, calf and quadriceps. You may need to use a slightly longer syringe or pen needle than you are used to (8mm minimum), and do not “pinch” the site when injecting. Instead, inject straight in (perpendicular to the skin) and push down hard to ensure that the muscle is reached. I’d like to note that intramuscular injection of insulin is not currently FDA approved and not well studied, so it should be used with caution.
Although intramuscular (IM) injections may sting momentarily, they are useful in situations when you want your insulin to work very fast, such as:
When you are ketotic due to a pump/infusion set malfunction, a missed injection, or spoiled insulin.
Any time you are dehydrated and hyperglycemic, as insulin does not absorb well from below the skin in a state of dehydration.
If your blood sugar is elevated soon before an important test or athletic event.
In case you missed a mealtime bolus and your blood sugar has gone quite high.
Healthcare providers have historically been reluctant to recommend intramuscular injections due to a perceived risk of infection or hypoglycemia. Having queried dozens of top experts in the diabetes field on the risks of IM injections, I have yet to find anyone who has seen these types of problems. However, as a precaution, it is best to cleanse the injection site and use a sterile one-time use syringe or pen needle when administering an IM injection.
2. Massage the area.
Anything that increases blood flow to the skin surface will accelerate the absorption of insulin. Massage is one such thing. Rubbing the area for several minutes within 15 minutes after injecting will help the insulin reach the bloodstream just a bit quicker.
3. Get into hot water.
Research has shown that taking a hot bath after taking a bolus causes insulin to dissipate from the subcutaneous site more rapidly. Hot showers, saunas, whirlpools, and even sunbathing may have similar effects. Just be careful about exposing insulin pumps and tubing to high temperatures as this can cause the insulin contained in these items to lose its potency.
4. Shake your booty.
Exercising the muscle that underlies the site of insulin injection (or infusion) will cause the insulin to reach the bloodstream more rapidly, so long as the exercise takes place within an hour after taking the insulin.
5. Use an air diffuser.
One thing I remember from chemistry is that small things naturally move faster than big things. I guess that’s why hulking seven-foot NBA centers can never keep up with speedy point guards. The same holds true for insulin. When insulin is delivered in the form of a large drop, the surface-area-to-volume ratio is quite low, so the diffusion rate is relatively slow. But if the insulin is delivered in the form of thousands of tiny droplets, the surface-area-to-volume ratio increases, and the molecules diffuse much more rapidly.
That’s exactly what happens when insulin is sprayed through the skin in the form of a “mist,” as occurs when using an air infuser or jet injector. By dispersing the insulin over a wide area under the skin in the form of micro-droplets, the insulin molecules diffuse through the subcutaneous fat quickly and reach the bloodstream more rapidly than they would as a traditionally-injected bolus. The difference isn’t huge (perhaps 15-20 minutes earlier to peak action), but every little bit helps.
Living with diabetes is all about overcoming challenges. Carb counting a cannoli. Rotating injection and infusion sites. And getting insulin to peak when we need it to. So despite the fact that “rapid” insulin falls far short of the job done by the pancreas and the pharmaceutical industry hasn’t quite figured out a solution, we are not without options. Now get out there and think even more like a pancreas!