A1c using Control IQ

I am wondering if anyone can provide information on the impact of Control IQ on their A1c number? I am especially interested if anyone is able to maintain an A1c of around 6 on the system? Thank you.

I was at 6.9 on my Medtronic system. In all fairness it was not looping, n
But I had cgm data. That’s when I decided to switch to tandem.
Just to make a change. I hear the guardian sensors are better now but back then I was afraid to go to bed with a glucose less than 110.
It took me time to fine tune my settings on tandem. But I saw a huge drop in my a1c pretty quickly.
I went to 6.3 and then I pushed it down to 5.4, but I was having lows.
My latest a1c was 5.9. And I’m happy with that. I’m ok with anything under 6.3 just as a psychological limit.
The system is set up to give you about a 6.3 but you can adjust it to get lower. Because even in sleep mode it targets 112 mg/dL.

I had to really work the settings to make this happen. It’s all in the insulin sensitivity and carb ratios. That is where I made the biggest changes between the two systems.

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Thank you.

My numbers were terrible before starting on the t:slim. Usually 9-13ish. Having the pump alone without any automation (but that also involved a switch to modern analog insulin), I was able to get into the 8s. When Basal-IQ rolled out, I got my first ever 7. Being on Control-IQ for a long time now, I’ve gotten 5.8 on my last two A1cs. I’m due another one, but I’m not expecting a change.

I run the pump in sleep mode all the time, so it tries to keep me around 110-120. My estimated A1c from CGM data is 5.4, but I always run a little higher in the lab test.

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I have been using Control IQ for over a year - started when it came out. My A1cs have been the best I’ve ever had - ALL under 6. Most recently was 5.7. I use sleep mode 24/7 though, as I didn’t like how the regular mode bolused. Works really well for me, especially in combo with intermittent fasting.

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My last two have been 5.4 and 5.7. I also run in sleep mode 24×7.

I started CIQ about a year ago, but used Medtronic pump plus cgm for over 30 years. My A1Cs have been in 5-6 range since using dexcom G4.

Now with CIQ, I get about the same A1C, but with less effort. I also use sleep mode 24 hours, for 112 target BG.

Interesting. I only use sleep mode when I’m sleeping and my last few A1c’s have been…6.3.
With just Basal-IQ I was around 6.9 or so.
My time in range (TIR) has been good, too – over 80% for the last several months. I’m pretty attentive to my diabetes, but don’t limit what kinds of foods I eat much.

My last A1C (pre-CIQ) was 6.5. I’m really curious to see what my next one will be, which will be my first since switching to tandem and ciq. I only use sleep mode at night though. Using it 24/7 seems to work for a lot of people, so maybe I’ll try it at some point.

Can u say a little more about having to work really hard with your settings? Does CIQ even use your basals ? Doesn’t the algo take over? Are you referring to your I:C ratios and sensititivity?

Yes, Control-IQ uses your programmed basal rates, amongst other settings. That’s why it’s so important to find which settings work for you… and why the system can be disappointing if your medical team can’t/won’t help you adjust them.

There are three different programs for intervention. Default Control-IQ, Sleep mode, and Exercise mode. They all have a different range in which Control-IQ leaves you to your own devices, but if you stray outside that range, it will either increase or decrease your programmed basal rates based on where your BG is predicted to be 30 minutes in the future. If you go to farther extremes, Control-IQ may even issue a correction bolus or suspend basal completely.

It’s different from Medtronic’s system in that you have more control over it and more variables that can be adjusted. It’s not giving micro-doses based on the limited information it knows at the time, but rather YOU provide the roadmap and the auto-pilot takes you on little detours when necessary.


Yes you put in rough settings and control iq makes minor adjustment throughout the day. It also gives bolus when you are headed for over 180. But I find I can bolus faster than the pump does.
The settings I changed were my weight, I added 20 lbs to my real weight. I changed carb ratio was 1:25 changed to 1:20
My correction factor changed it lower from 1:35 down to 1:18
This allowed me to make the pump more aggressive than it was meant to be and keeps me a little lower overall

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Thank you so much everyone. I will not have the support of a knowledgeable team to help get the system optimized so I would do it on my own. It does sound like some of you are able to adjust the settings to get your A1cs to 6 or under. I would love less work. I have used a pump and cgms for many years and use the fastest acting insulins, Fiasp,Apidra and will try the newest one when my insurance changes. One of my concerns is that the system is not geared to those faster insulins. If any of you use those insulins and make the system work for you let me know.

Tandem has folks who do a one-on-one training session with people new to the pump. Hasn’t anyone you’ve talked to mentioned this? If you haven’t already, try asking Tandem about setting up a session with a pump trainer. Perhaps?

At the very least, watch their YouTube training videos.

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Hi Jim, Can you explain a little more how you use the ci

ciq for 24 hours? Can you exercise? Do you eat a special diet? Thanks!

Hi @ali8,
I’ve seen my Hga1c drop from 7 to 6.2-6.3. I don’t want to go any lower. How is it working for you? It has been a great help in improving my daily outlook and health in so many ways! Good Luck!

A1c 6.7/6.8 before CIQ, now 6.1 for the last 4 quarters using it.

Thank you. I have been on different pumps for years:). It is the fine tuning the settings for the Control IQ program and also for Fiasp/apidra with the program i am concerned about. As soon as I mention using Fiasp in the pump Tandem tends to clam up. I read that that a possible work around to the 5 hour action time is to adjust the sensitivity and carb ratios:). I can just play around with it:) and keep looking at other tips, like the adding some pounds to your weight number.

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I don’t think the 5 hour duration of insulin action will matter much. The algorithm Tandem uses for Control-IQ is very different than any other pump algorithm you’re used to. It’s actually very dynamic and flexible. It also includes the long tail where the insulin action is tapering off into nothingness, hence why it’s so long. The traditional “curvilinear” model we’re used to really only incorporated the steep bits of the action curve, and we had to fudge the DIA setting around trying to figure out how much of the minimal action stuff we cared about. Essentially square peg, round hole… The old algorithm just didn’t match up with what our insulin was actually doing. Control-IQ lines up really well with anyone who was using 2.5-4ish hours previously.

The reality is, the action curves are so similar, that it just doesn’t matter. The only real difference is in the first 15 minutes or so. It peaks faster, but then they become very similar. Control-IQ isn’t making any major adjustments within 60 minutes of a bolus anyway, so it doesn’t matter what those early minutes look like.


Your settings will need adjusted anyway, so there’s no way to tell why. Basal test first, then watch how control-IQ affects your BG. If it keeps you in gently rolling waves around your target, perfect. If it is over-correcting and your chart is all spikey up and down, you need to raise the CF setting to a higher number. If you’re stuck in whatever direction your BG is heading and you wish you could give Control-IQ a kick in the virtual pants to make it work harder/faster, then lower CF to a smaller number.

The problem you’re going to face is that both FIASP and Apidra tend to occlude in the pump. It’s not 100% likely, but it’s true for most people. Tandem is a closed system with an isolated reservoir of insulin. It causes more pressure in the reservoir than the direct-line pumps, and the insulin actually crystalizes and clogs up the works.

If you search this site, there plenty of posts talking about success with mixing them with small amounts of Humalog/Novolog (stick with the same manufacturer!). Just a small amount of the slower acting insulin seems to prevent the crystallization, while not affecting the speedy peak.

Thankfully, the new Lyumjev doesn’t seem to have this problem. I haven’t seen any reports of Tandem occlusions with it.

No Tandem rep will EVER talk to you about FIASP/Apidra. They’re not allowed to. These insulins weren’t included in their clinical trials (probably because they already knew they were troublesome), and they’re not allowed to talk about anything outside the scope of their FDA approval.