Insulin Tips: Pre-Bolus, Protein Bolus & IM Shots

In addition to the Law of Small Numbers, there are numerous other tips and recommendations to better control blood glucose levels. The entire goal of Dr. Bernstein's plan of low carb eating is to get off the daily rollercoaster of blood glucose levels that constantly go high, then low, and back to high again. Here are a few of the insulin recommendations


Since our bodies do not release insulin immediately upon eating, we have to be smart and try to mimic nature as best we can. Problem is, even rapid-acting injected insulin can't start working as quickly as our own body's insulin would.

A pre-bolus sounds easy enough. Inject your food bolus 10-30 minutes before eating in order to most accurately mimic the primary insulin response of a non-diabetic. This will (nearly) guarantee your blood sugar does not spike before your insulin starts to work. 

If you use a CGM (Continuous Glucose Monitor) you can see when your blood glucose levels start to rise after you eat and plan accordingly to cover it with a bolus at your next meal (or reversely, watch your CGM to see when your insulin starts to work, then eat your meal.) 

There are a few caveats/disclaimers for pre-boluses:

  1. A pre-bolus of 10-30 minutes before eating is applicable for those using a rapid-acting insulin such as Novolog/Novorapid, Humalog and Apidra. If you are using Regular (R) insulin, you will need to bolus substantially earlier (45-60 minutes before eating). There are several charts that show insulin action times, such as this one. Please use these as a guide, but remember that each person is unique and this is only a guide.

  2. If you are experiencing delayed stomach emptying (gastroparesis), which can be a complication of diabetes, DO NOT PRE-BOLUS! This can lead to dangerously low blood glucose levels due to slowed digestion.

  3. If you try a pre-bolus and your blood sugar is low while eating, or immediately after eating, you may need to adjust the timing of your pre-bolus, or watch for your blood glucose level to start to rise (meaning your food is being digested) and bolus accordingly at that time.

  4. All pre-bolusing requires a guaranteed eating time and food amount. This is best done at home or in a place where you can control the meal time and amounts. Pre-bolusing at a restaurant can create problems if your food is delayed or is delivered to you in a different quantity/presentation than what your pre-bolus can cover. This isn't as much of a problem when eating low carb and following the Law of Small Numbers, but still something to be aware of.

Read more about pre-bolusing in Dr. Bernstein's Diabetes Solution, chapter 19, page 301.


Protein Bolus:

Before starting low carb, people may (or may not) notice that their blood glucose levels will spike 2-5 hours after eating a protein-heavy meal due to gluconeogenesis (the body's conversion of protein into glucose). Once you switch to low carb eating and blood glucose levels are steadier, the spike is very obvious, and especially large after eating red meat.

In this case, you will need to take an additional, later bolus to cover the protein that you eat.  

My protein spike for red meat comes 5 hours after eating. Because of this, I try to eat red meat earlier in the day, keep portions limited to 4-5 ounces of meat, watch for the spike, then take up to 2.5 units of insulin to cover the protein conversion to glucose. 

Chicken, fish and pork require a much smaller and earlier protein bolus for many. For me, I may need 1 additional unit of insulin, delivered 2.5 hours after eating. **This is slightly different for everyone and depends on how much you eat, and how fast your body converts protein to glucose. 

Gluconeogenesis is described in detail in Dr. Bernstein's Diabetes Solution, Chapter 6 , page 96.  And bolusing for protein is covered in Dr. Bernstein's Diabetes University on YouTube. 

**Keep in mind that Dr. Bernstein recommends Regular (R) insulin and not fast-acting (in most cases).  Since Regular insulin has a much slower onset and a much different active range than the fast-acting insulins, the range of time that it covers often corresponds with the delayed protein spike due to gluconeogenesis. This is not the case with fast-acting insulins, thus requiring a second bolus to cover protein if you are using fast-acting insulin. 


IM Shots: 

IM (intramuscular) shots go against what many of us were taught about insulin injections. We were told to due subcutaneous injections (meaning to to pinch your skin and inject into the fatty layer, just under the skin.) 

An intramuscular injection is just what the name suggests, an insulin injection that goes into muscle, rather than just into the fatty layer under the skin. The benefit is a much higher rate of absorption and much faster response time. Intramuscular shots are a great tool to use when blood glucose levels are higher than you'd like and you want to get them back to normal range quickly.

Most people require a longer length needle (1/2"/12.7 mm), and an injection into the deltoid/shoulder muscle for IM shots. If you are especially lean, or you're injecting into a child, a standard needle syringe may be fine. If you are heavier, the deltoid muscle might be more difficult to reach. 

After an IM shot, I see a full drop of blood glucose level within 60-90 minutes, rather than 3-4 hours when using a subcutaneous injection by a syringe or insulin pump bolus. I discussed this previously after missing a bolus. 

I use IM shots on a regular basis without having problems of low blood glucose levels BUT I ONLY USE SMALL IM injections of 2-5 units. 

It is a personal decision to use IM shots to lower your blood glucose levels more rapidly. Some choose to not use them at all and stick with subcutaneous injections. Others correct with IM shots whenever their blood glucose goes over 120 mg/dL. Always try IM shots with a very small insulin dose first. 

IM Shots are discussed in Dr. Bernstein's Diabetes Solution, chapter 19, page 324. 

Using these three insulin management tools of pre-boluses, protein boluses and IM shots, (along with the overlying concept of The Law of Small Numbers) you can maintain your blood glucose levels at much steadier numbers, and avoid damaging high glucose levels that lead to major health complications of Diabetes. 

If you're new to low carb and haven't purchased Dr. Bernstein's Diabetes Solution book, click here to get it on Amazon.