Tandem Diabetes and Dexcom – Big Winners with Control-IQ + World’s First Interoperable Closed Loop
The long-awaited Tandem Diabetes’ Control IQ AID software was FDA approved December 13, 2019 and became available in January, 2020, as the world’s first fully interoperable closed loop. Interoperability means that the parts are interchangeable so when a better version of one component becomes available, the user is no longer saddled with outdated and less accurate equipment for years until their insurance company replaces the whole system.
A fully interoperable artificial pancreas requires three components: an interoperable CGM or iCGM (currently only Dexcom’s G6), an alternate controller enabled pump or ACE Pump (currently Tandem’s t:slim X2 and Omnipod Dash), and an interoperable software controller or iController (currently Tandem’s Control-IQ). An iController automatically adjusts insulin delivery from an insulin pump in response to glucose readings from a CGM. Tandem integrated its Device Updater software into the t:slim X2 insulin pump in late 2016 to enable convenient software upgrades over the internet without the need to replace the pump itself. Tandem Diabetes and Dexcom are the first companies to create a fully interoperable system with the needed i-components.
How Control-IQ Works
Control-IQ uses the TypeZero/Dexcom hybrid closed loop (HCL) algorithm that relies on all the normal pump settings (basal profile, insulin-to-carb ratio, insulin sensitivity factor). However, users must still bolus before meals and match bolus doses to carbs consumed or some other food measurement system. The duration of insulin action (DIA) or active insulin time (AIT) is pre-set at a saner and much safer 5 hours to minimize insulin-stacking as glucose levels are improved. Although other AID systems allow the user to set their DIA between 2 to 6 hours, the shorter times do not accurately reflect how long the insulin works in the body, often resulting in hidden insulin stacking and low glucose readings. Using the predicted CGM value in 30 minutes, Control-IQ improves time between 70-180 mg/dl (3.9 to 10.0 mmol) with these strategies:
- For a predicted glucose above 180 mg/dl, it adds as much as 60% of a full correction bolus with a target of 110 mg/dl, besides increasing the basal rate
- For a predicted glucose above 160 mg/dl, it increases the basal rate
- Between 112.5-160 mg/dl, it maintains the default user settings
- For a predicted glucose below 112.5 mg/dl, it decreases basal insulin
- For a predicted glucose below 70 mg/dl, it turns off basal insulin
During the day, the system targets the 112.5 to 160 mg/dl range but becomes more aggressive at night with a breakfast goal of 112.5-120 mg/dl. Control-IQ also offers an “exercise mode” that changes the target to 140 to 160 mg/dl in order to reduce hypoglycemia.
Control-IQ Research Results
Tandem’s Control-IQ HCL pivotal trial evenly divided 168 participants ages 14-71 into those on the Control-IQ HCL compared to those on the same pump and CGM without the Control-IQ algorithm. Unlike most research studies, all 168 participants completed the six month study, and spent 92% of the six months in active closed loop mode. Results for all 168 participants on Control-IQ:
- Time between the 70 to 180 mg/dL range improved by 2.6 hours per day with Control-IQ (70% vs. 59%), with most of the improvement resulting from less time spent above 180 mg/dl.
- Time-in-Range improved for both those with initially low A1Cs and those with high A1Cs.
- A1C was lowered by 0.3% from 7.4% to 7.1% with Control-IQ.
- Average glucose was 14 mg/dl lower at 156 mg/dl vs. 170 mg/dl with Control-IQ.
- Time below 70 mg/dl was reduced by 13 minutes a day, or more than 6 hours per month.
What Participants Thought about Control-IQ
In a post-study questionnaire, people scored Control-IQ:
- 8/5 on desire to continue using
- 7/5 on ease of use
- 6/5 on usefulness
- 5/5 on trust
History of iAIDs
In the past, wearers of diabetes devices would be encumbered with outdated and less accurate equipment for years until their insurance company replaced the entire system. If a particular component such as a more accurate CGM became available, it would not work with other components nor those of another manufacturer. This shackled device wearers to one manufacturer when another offered improved technology.
The Juvenile Diabetes Research Foundation (JDRF) addressed this issue in August 2017 by encouraging the FDA to consider an Open Protocols Initiative to allow plug and play iAID components to be readily interchanged to give users more choices and better access. Seven months later in March 2018, the FDA introduced the first component in a full plug and play iAID system when it approved Dexcom’s G6 CGM as the first (and so far only) interoperable plug and play iCGM.
Dexcom earned the iCGM designation by demonstrating sufficient glucose accuracy and the ability to work interactively with an ACE Pump or iController through BLE communication to securely share glucose data. Neither of the other components existed in 2018. Tandem added the second component in February 2019, when the FDA awarded its t:slim X2 pump an ACE designation. Then Friday, December 13, 2019, became a landmark for people with insulin-requiring diabetes with approval of Control-IQ and the first iAID. See our complete analysis of Current Closed Loop Options.