How to use Dexcom CGM Trend Arrows for Insulin Adjustments

In the event you use a CGM (Steady Glucose Monitor), you most likely already understand how a lot of a game-changer this expertise will be relating to managing your diabetes.

Having perception into our blood glucose historical past, the place what our blood sugar is correct now, and the place it’s headed brings peace of thoughts and makes managing diabetes lots simpler and safer.

However even if you happen to love your CGM, do you make the most of the development arrows for insulin changes? If not, you’re actually lacking out on the total potential of the expertise.

By being attentive to the CGM development arrows, you’ll have the ability to make extra proactive and knowledgeable decisions relating to adjusting your insulin doses.

The data on this put up is particular to the Dexcom CGM system. Different CGM methods use development arrows as effectively, however they might have totally different meanings so please watch out using the data right here if you happen to use one other system.

Once you open your Dexcom app or take a look at your receiver, you’ll see your present blood sugar in addition to a sign of what your blood sugar might be in half-hour.

That indication comes within the type of arrows. On the receiver, the arrows are to the fitting of your present blood sugar. Within the app, it’s proven as a circle along with your blood sugar and the arrows across the circle.

You most likely know that an up arrow signifies that your blood sugar is rising and a down arrow that it’s falling, however have you learnt by how a lot and learn how to embrace it in your insulin changes?

Let’s begin with what the arrows point out in accordance with the producer:

Supply: Dexcom G6 information

Actual-life instance

Let’s say my blood sugar is 120 mg/dL (6.7 mmol/l) and my Dexcom is exhibiting 2 arrows straight up.

On this case, I can anticipate my blood sugar to doubtlessly improve to above 210 mg/dL (120 + 90) inside the subsequent 30 min.

I attempt to keep beneath 200 mg/dL so I’d almost certainly give myself a correction bolus primarily based on this information (so long as I didn’t simply eat a meal or have already got sufficient lively insulin on board that simply hasn’t kicked in but).

Your CGMs arrows will be extremely useful for blood sugar administration — however provided that you understand how to answer these arrows.

A number of medical professionals have provide you with approaches for utilizing CGM arrows to assist sufferers dose insulin safely and successfully. Most significantly, all of them agree that we must always take the rise or fall fee into consideration when adjusting our insulin doses. What they disagree on, nevertheless, is strictly how insulin doses needs to be adjusted primarily based on these arrows.

The Endocrine Society reviewed 4 revealed approaches in 2017 and got here up with their very own tips. Their tips had been revealed within the Journal of the Endocrine Society in December 2017 (please word that the rules mentioned listed here are for adults solely). 

Since I take into account the Endocrine Society the best authority relating to any such suggestion, I’m going to share their suggestion with you.

Though the rules had been written for Dexcom G5, no adjustments have been made to the arrows for the newer methods and the suggestions needs to be legitimate for Dexcom G6 as effectively.

The Endocrine Society recommends that you just alter your insulin primarily based on what your blood sugar might be in half-hour, somewhat than what it’s proper now. However as a substitute of calculating what your future blood sugar might be in half-hour, they advocate that you just alter your correction issue (CF).

This correction needs to be made on high of any correction to your present blood sugar in addition to any carbohydrates consumed.

Your CF is how a lot one unit of rapid-acting insulin (like Humalog or Novolog) will lower your blood sugar. In the event you use a pump, you’ll be able to see your CF in your settings. In the event you handle your diabetes with injections and don’t know your CF, you’ll be able to ask your medical workforce that can assist you calculate it.

Endocrine Society’s beneficial correction primarily based on Dexcom development arrows

Supply: https://educational.oup.com/jes/article/1/12/1445/4642923

Let’s sum it up with an instance:

I’ve simply rolled away from bed within the morning, had no lows in a single day, and I’m about to take a seat down for a meal of 20 grams of carbohydrates. My blood sugar is 120 mg/dL (6.8 mmol/l) with two arrows up. Which means I’ll need to do three calculations:

1. First, I’ve to calculate the dose for my carbs. Assuming my Insulin to Carb Ratio (ICR) is 10, I’d want 2 IU of insulin to cowl my 20 grams of carbs.
2. Secondly, I’ll need to calculate my correction dose primarily based on my present blood sugar. If my CF is 25 and my goal blood sugar is 95 mg/dl (5.3 mmol/l), my correction dose is 1 IU (120-95 = 25 and 25/25 = 1 IU).
3. Thirdly, I’d need to calculate the correction primarily based on the arrows. Since I’ve two arrows up and my CF is 25 in accordance with the suggestions, I’ll want a 3.5 IU correction.

Including all that up my whole dose can be 2 IU + 1 IU + 3.5 IU = 6.5 IU. 

Had my blood sugar been decrease than my goal or had I seen downwards arrows, I’d have ended up with a decrease beneficial dose.

Simply to make it possible for is smart, let’s do one other instance:

I once more simply rolled away from bed and am about to take a seat down for a meal of 20 grams of carbohydrates, however now my blood sugar is 120 mg/dL (6.8 mmol/l) with one arrow straight down.

All that modified in comparison with the final instance is the path of the arrow, which adjustments calculation #3.

Since I now have one arrow straight down and my CF is 25, in accordance with the suggestions I’ll want a -2.5 IU correction.

Including all that up, my new whole dose can be 2 IU + 1 IU – 2.5 IU = 0.5 IU 

Phew, that’s plenty of math. Take a look at the following part on how I’d simplify it.

The endocrine suggestions make full sense to me, however it’s plenty of math! In addition they don’t can help you take lower than 0.5 IU in correction (which will be a difficulty if you happen to’re very insulin delicate).

I’d somewhat use a bolus calculator than do all that math each time I must bolus for a meal or a correction dose. You probably have a pump, you almost certainly have a built-in bolus calculator. If you’re on a number of every day injections (MDI) like me, you’ll need to look elsewhere.

Previously, I’ve used an app referred to as RapidCalc for these calculations. I now use InPen, a SmartPen that sends information on to my cellphone through Bluetooth and has an related app that calculates doses and retains observe of IOB.

The InPen app and RapidCalc mainly do the identical as a bolus calculator, aside from really giving me my dose (please word that the RapidCalc app will not be FDA-approved).

After ending the bottom calculation in your bolus calculator, you’ll be able to then manually add within the development arrow correction primarily based in your CF.

Bear in mind to react primarily based on what you’ll be doing the following 1 to 4 hours, not on what you’re doing if you’re about to bolus.

In the event you’re planning to train or simply transfer greater than standard (like go for a stroll, buying, cleansing, gardening, and so on.) you won’t must react as aggressively as the rules state.

Usually, it’s beneficial that you just scale back your bolus and doubtlessly additionally your basal (if you happen to use a pump) earlier than train. As a result of common speedy insulin is lively within the physique for as much as 4 hours (some even see a tail as much as 6 hours after injection), you’ll want to assume earlier than you bolus.

There are new ultra-fast-acting insulins obtainable now and the endocrine tips don’t work for these. In the event you use Afrezza or Fiasp, please know that these insulins peak a lot sooner, and making use of the calculations proven above might doubtlessly be extraordinarily harmful.

When to NOT use the CGM development arrows

All of the publications advocating for utilizing the development arrows for making insulin changes additionally state that there are some conditions the place you need to completely NOT use them or a minimum of take extreme precautions.

In the event you plan on beginning to make changes to your insulin dose utilizing development arrows, please learn these precautions first.

4-hour consuming window

The Endocrine Society recommends that the development arrows aren’t used throughout the 4 hours after having a meal with a bolus. As a substitute, they advocate the next:

• 2 hours post-meal – Don’t right excessive blood sugars to forestall insulin stacking
• 2-4 hours post-meal, blood sugar 150-250 mg/dL (8.3-13.9 mmol/l) with one or two arrows up – Think about using CF to regulate
• 2-4 hours post-meal, blood sugar >250 mg/dL (13.9 mmol/l) with one or two arrows up – Affirm with a fingerstick, take a look at for ketones (if >300 mg/dL/16.7 mmol/l), right utilizing injections, if after 1 hour you continue to see two arrows up, repeat
• 2-4 hours post-meal, blood sugar close to 150 mg/dL (8.3 mmol/l) with one arrow barely down – Verify once more in 30-min
• 2-4 hours post-meal, blood sugar close to 150 mg/dL (8.3 mmol/l) with one or two arrows down – Verify once more in 15-min
• 2-4 hours post-meal, blood sugar close to 100 mg/dL (5.6 mmol/l) with one arrow barely down OR one arrow down – Contemplate consuming 15 g of carbs, recheck in 20-min. If >70 mg/dL (3.9 mmol/l) and downward arrows, affirm with a fingerstick and take into account one other 15 g of fast-acting carbs 
• 2-4 hours post-meal, blood sugar close to 100 mg/dL (5.6 mmol/l) with two arrows down – Comply with the directions above (f) however eat 30 g carbs

Quickly rising blood sugar

In the event you see 2 arrows up in your receiver or app earlier than a meal, it’s beneficial that you’re diligent along with your pre-bolus and inject your insulin 15 to twenty min earlier than consuming.

Quickly lowering blood sugar

In the event you see 2 down in your receiver or app earlier than a meal, it’s beneficial that you just wait and inject your insulin if you begin consuming, or if you happen to’re near 150 mg/dL (8.3 mmol/l) maintain off and don’t inject till you see your BGs leveling off.

Fragile / older adults

For fragile or older adults, the Endocrine Society recommends a much less aggressive insulin dose adjustment to restrict the chance of hypoglycemia.

For upward-rising arrows, they advocate a 50% discount of the recommended adjustment (e.g. from 1 IU to 0.5 IU), and for downward arrows, they advocate a 50% improve in discount (e.g. from 1 IU to 2 IU).

Sick day administration and medicine concerns

Sure drugs, each prescription and OTC, can intrude along with your CGM readings, and development arrows ought to consequently not be used for insulin changes. Somewhat than relying fully in your CGM, accompany your CGM readings with finger sticks. 

At all times use widespread sense earlier than dosing

As with all instrument in our diabetes instrument package, I’d encourage you to by no means simply apply the suggestions blindly.

You probably have a sense that the beneficial dose could be off, typically counting on how effectively you already know your physique is the way in which to go.

Though the Dexcom G5 and G6 CGMs are accredited for dosing by the FDA, they will typically be inaccurate, so I’ll all the time affirm with a fingerstick earlier than making any massive dosing changes.