When you use a CGM (Steady Glucose Monitor), you most likely already understand how a lot of a game-changer this expertise may be with regards to managing your diabetes.
Having perception into our blood glucose historical past, the place what our blood sugar is true now, and the place it’s headed brings peace of thoughts and makes managing diabetes rather a lot simpler and safer.
However even in case you love your CGM, do you make the most of the pattern arrows for insulin changes? If not, you’re actually lacking out on the total potential of the expertise.
By taking note of the CGM pattern arrows, you’ll be capable of make extra proactive and knowledgeable decisions with regards to adjusting your insulin doses.
The data on this put up is restricted to the Dexcom CGM system. Different CGM methods use pattern arrows as properly, however they could have completely different meanings so please watch out using the data right here in case you use one other system.
Whenever you open your Dexcom app or have a look at your receiver, you’ll see your present blood sugar in addition to a sign of what your blood sugar will probably be in half-hour.
That indication comes within the type of arrows. On the receiver, the arrows are to the correct of your present blood sugar. Within the app, it’s proven as a circle together 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 are you aware by how a lot and methods to embody it in your insulin changes?
Let’s begin with what the arrows point out in accordance with the producer:
| Development Arrows | Which means |
| 2 arrows straight up | BG might enhance greater than 90 mg/dL (5 mmol/L) in 30 min. |
| 1 arrow straight up | BG might enhance as much as 90 mg/dL (5 mmol/L) in 30 min. |
| 1 arrow barely up | BG might enhance 30-60 mg/dL (1.7-3.3 mmol/L) in 30 min. |
| 1 arrow to the aspect | No BG enhance or lower of greater than 1 mg/dL (0.05 mmol/L) per min. |
| 1 arrow barely down | BG might lower 30-60 mg/dL (1.7-3.3 mmol/L) in 30 min. |
| 1 arrow straight down | BG might lower as much as 90 mg/dL (5 mmol/L) in 30 min. |
| 2 arrows straight down | BG might lower greater than 90 mg/dL (5 mmol/L) in 30 min. |
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 probably enhance 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 energetic insulin on board that simply hasn’t kicked in but).
Your CGMs arrows may be extremely useful for blood sugar administration — however provided that you understand how to reply to 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 should always take the rise or fall price under consideration when adjusting our insulin doses. What they disagree on, nonetheless, is strictly how insulin doses must be adjusted primarily based on these arrows.
The Endocrine Society reviewed 4 printed approaches in 2017 and got here up with their very own pointers. Their pointers have been printed within the Journal of the Endocrine Society in December 2017 (please observe that the rules mentioned listed below are for adults solely).
Since I take into account the Endocrine Society the very best authority with regards to any such advice, I’m going to share their advice with you.
Though the rules have been written for Dexcom G5, no adjustments have been made to the arrows for the newer methods and the suggestions must be legitimate for Dexcom G6 as properly.
The Endocrine Society recommends that you just alter your insulin primarily based on what your blood sugar will probably be in half-hour, fairly than what it’s proper now. However as a substitute of calculating what your future blood sugar will probably be in half-hour, they advocate that you just alter your correction issue (CF).
This correction must be made on prime of any correction in 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. When you use a pump, you possibly can see your CF in your settings. When you handle your diabetes with injections and don’t know your CF, you possibly can ask your medical staff that will help you calculate it.
Endocrine Society’s really useful correction primarily based on Dexcom pattern arrows
| Arrows exhibiting | Correction Issue (CF) | Correction dose (IU) |
| 2 arrows straight up | <25 25-50 50-75 >75 | +4.5 +3.5 +2.5 +1.5 |
| 1 arrow straight up | <25 25-50 50-75 >75 | +3.5 +2.5 +1.5 +1 |
| 1 arrow barely up | <25 25-50 50-75 >75 | +2.5 +1.5 +1 +0.5 |
| 1 arrow to the aspect | <25 25-50 50-75 >75 | No adjustment No adjustment No adjustment No adjustment |
| 1 arrow barely down | <25 25-50 50-75 >75 | -2.5 -1.5 -1- 0.5 |
| 1 arrow straight down | <25 25-50 50-75 >75 | -3.5 -2.5 -1.5 -1 |
| 2 arrows straight down | <25 25-50 50-75 >75 | -4.5 -3.5 -2.5 -1.5 |
Supply: https://educational.oup.com/jes/article/1/12/1445/4642923
Let’s sum it up with an instance:
I’ve simply rolled off the 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:
- 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.
- 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).
- 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 really useful dose.
Simply to ensure that is sensible, let’s do one other instance:
I once more simply rolled off the 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 course 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, nevertheless it’s plenty of math! In addition they don’t will let you take lower than 0.5 IU in correction (which may be a problem in case you’re very insulin delicate).
I’d fairly use a bolus calculator than do all that math each time I have to bolus for a meal or a correction dose. If in case you have a pump, you probably have a built-in bolus calculator. If you’re on a number of day by 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 knowledge on to my cellphone through Bluetooth and has an related app that calculates doses and retains monitor of IOB.
The InPen app and RapidCalc mainly do the identical as a bolus calculator, apart from truly giving me my dose (please observe that the RapidCalc app is just not FDA-approved).
After ending the bottom calculation in your bolus calculator, you possibly can then manually add within the pattern 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 while you’re about to bolus.
When you’re planning to train or simply transfer greater than normal (like go for a stroll, procuring, cleansing, gardening, and so on.) you won’t have to react as aggressively as the rules state.
Typically, it’s really useful that you just cut back your bolus and probably additionally your basal (in case you use a pump) earlier than train. As a result of common speedy insulin is energetic within the physique for as much as 4 hours (some even see a tail as much as 6 hours after injection), you must assume earlier than you bolus.
There are new ultra-fast-acting insulins obtainable now and the endocrine pointers don’t work for these. When you use Afrezza or Fiasp, please know that these insulins peak a lot sooner, and making use of the calculations proven above might probably be extraordinarily harmful.
When to NOT use the CGM pattern arrows
All of the publications advocating for utilizing the pattern arrows for making insulin changes additionally state that there are some conditions the place you must completely NOT use them or a minimum of take extreme precautions.
When you plan on beginning to make changes to your insulin dose utilizing pattern arrows, please learn these precautions first.
4-hour consuming window
The Endocrine Society recommends that the pattern arrows will not be 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 appropriate excessive blood sugars to stop 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, check for ketones (if >300 mg/dL/16.7 mmol/l), appropriate 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 – Think about 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
When you see 2 arrows up in your receiver or app earlier than a meal, it’s really useful that you’re diligent together with your pre-bolus and inject your insulin 15 to twenty min earlier than consuming.
Quickly lowering blood sugar
When you see 2 down in your receiver or app earlier than a meal, it’s really useful that you just wait and inject your insulin while you begin consuming, or in case you’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 danger of hypoglycemia.
For upward-rising arrows, they advocate a 50% discount of the steered adjustment (e.g. from 1 IU to 0.5 IU), and for downward arrows, they advocate a 50% enhance in discount (e.g. from 1 IU to 2 IU).
Sick day administration and drugs concerns
Sure drugs, each prescription and OTC, can intrude together with your CGM readings, and pattern arrows ought to consequently not be used for insulin changes. Quite than relying utterly in your CGM, accompany your CGM readings with finger sticks.
All the time use frequent sense earlier than dosing
As with all instrument in our diabetes instrument equipment, I’d encourage you to by no means simply apply the suggestions blindly.
If in case you have a sense that the really useful dose may be off, typically counting on how properly your physique is the best way to go.
Though the Dexcom G5 and G6 CGMs are authorised for dosing by the FDA, they’ll typically be inaccurate, so I’ll at all times affirm with a fingerstick earlier than making any giant dosing changes.
