Virtual Slipstream 2021 happened April 22-24. We had the team from Tandem Diabetes Care Canada join us to share more more about Control-IQ and how it functions in the real world. Miss the session? Read on to find out the top things learned during Tandem Diabetes Care’s session: Control-IQ-Technology in the Real World.
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At Virtual Slipstream 2021, Lorraine Anderson of Tandem Diabetes Care and Evelyn Riddell, a Control-IQ user, joined us for a deep dive into Control-IQ technology.
Lorraine Anderson, RD, CDE, is a Registered Dietitian and Certified Diabetes Educator. She has had the privilege of presenting workshops across Canada to both health care professionals and families who live with type 1 diabetes. When not at work, she is a busy mom and stepmom to six young adults and two golden retrievers. Lorraine can be found at a dog park, on a hiking trail, tennis court, golf course or ski hill. She have lived with diabetes for over 30 years and understands firsthand the ups and downs of daily life with diabetes. Evelyn Riddell is a full-time student at the University of Toronto, research assistant, and part time model. She believes strongly in the power of representation and raises awareness for diabetes through social media, advocacy, and public speaking.
Here are some key takeaways, in case you missed their presentation.
Control-IQ Overview
Lorraine gave us a high level overview of the Control-IQ system. To explain it most simply, it uses an Inuslin Pump (Tandem’s t:slim X2), a Continuous Glucose Monitor, or CGM (Dexcom G6) and an advanced algorithm to help ramp up basal rates when blood glucose (BG) levels are trending high, pull back basal rates when BGs are trending low, and throw in automatic correction boluses when needed. The automatic correction boluses is a unique feature to the Control-IQ pump and what allows it to be labelled as an ‘Advanced’ Hybrid Closed-Loop. System.
Control-IQ uses what is called a metabolic algorithm, meaning that the algorithm is built to mimic the metabolism and physiology of insulin itself. This means that the system does require you to enter some settings and the more accurate those settings are, the more success you’ll have on a pump. The settings required are: Basal Rates/Basal Profile, Insulin to Carb Ratio, and Correction Factor. This is an important consideration as it is not uncommon for people with Type 1 to compensate for errors in one setting, with another setting. For example, sometimes we have basal rates set that automatically compensate for our meals, meaning that our carb to insulin ratio may actually be quite different at certain meals than we expect. It’s important to the Control-IQ system that these settings are accurate to have the greatest benefit on the system.
During clinical trials with Control-IQ, on average, people found an increase in time in range of 10-11%. That translates to, at minimum, a .5% increase in A1C.
What triggers the algorithm to get to work?
As mentioned previously, the Control-IQ algorithm dials up basal when you’re predicted to be high, dials back basal when you’re predicted to be low, and also can provide correction boluses. But when do these things kick in?
First of all, the algorithm is always looking at predictions 30 minutes in the future. Anytime glucose is predicted to be between 6.2mmol/L and 8.9mmol/L, you’ll be cruising along, getting your regularly programmed basal rate. As soon as the system predicts that you’ll be above 8.9mmol/L, it will ramp up your basal rate to correct. As soon as it predicts you’ll be over 10mmol/L, you’ll get a bolus correction to help bring you back into range faster.
On the flip side, if the system predicts you’ll be below 6.25 mmol/L, you’ll get a decreased basal rate. If you happen to hit 3.9mmol/L, your pump will suspend completely.
Duration of Insulin Action
One question that came up during this session was why the Control-IQ system uses a Duration of Insulin Action of 5 hours, when most people are used to using 2-4 hours in other pump systems. Lorraine showed the group a graph of insulin action for rapid-acting insulin and pointed out that although insulin is MOST active during the 2-4 hour window, there is still a ‘tail’ during the 5-6 hour period when up to 4% of the insulin dose given is still active. Although this is quite minuscule and often unimportant in a non hybrid-closed-loop system, it becomes very important in the Control-IQ system to help avoid insulin stacking.
A 5 hours Duration of Insulin Action was found during trials to provide the least amount of hypoglycemia with the greatest time in range.
Tips for Success
Finally, Lorraine and Evelyn provided the group with Tips for Success in starting on Control-IQ:
Set a programmed sleep schedule
The Sleep Activity in the Control-IQ system allows for a tightened target range of 6.25mmol/L – 6.6mmol/L, rather than 6.6 – 8.9mmol/L when not using the Sleep Activity. When using the Sleep Activity, correction boluses are not given. Instead the system relies solely on basal rate adjustments to correct for predicted highs.
Use Exercise Activity 60 mins ahead of time
Another feature of the Control-IQ system is the Exercise Activity. The Exercise Activity sets a target between 7.8 and 8.9mmol/L. Lorraine suggests ensuring that the Exercise Activity is turned on at least 60 minutes before starting exercise, if possible.
Bolus before eating and be sure to enter your carbs
Entering carbs on the Control-IQ system is very important, as is bolusing before you eat. The algorithm understands changes in BGs from carbs eaten differently than changes for other reasons. The system will also start to correct rising BGs from missed carb entries or meal boluses quite quickly, which could lead to improper dosing if you bolus for your food AFTER you have eaten.
Consider treating BGs with less carbs
You may find that you require fewer carbs to correct a low than you have used in the past. Keep a keen eye out for this!
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