Frustration with CIQ and inaccuracies in CGM

I’ve not made a post here but I’ve lurked for a little while. (Hi, I’m Lauren!) I’ve had diabetes since November 2014 and just started using the Tandem T Slim x2 pump back in July/August of 2022. I liked it a lot at first, but as my needs changed and things needed to be scaled back (due to me having lows), I have enjoyed it far less. I’m almost at the point where I want to give up as much as I like it some days.

I’m using the Dexcom g6 in conjunction with the pump for Control IQ and let me tell you some days I really hate it. More than once I’ve had CIQ issue a correction bolus when I didn’t need it, only leading me to a low and a lot of distress (I suffer from extreme anxiety, not just from diabetes). Just 40 minutes ago it happened again, and I’m now sitting watching my numbers after having a snack to cover what it gave me since it thought I was rising when in reality I wasn’t going to get anywhere near 180.

In any case, I’m really starting to get frustrated every day- I’m either too high or going low and I feel out of control again. Some days it feels like I’d be better off going back to injections just because ever since getting on the pump I’ve been nearly invalid. I can’t go out and do things because as soon as I start walking around after a meal, I drop. (even in exercise mode) If I don’t bolus for the full meal, I’m too high later on. My “best” days are ones where I’m essentially housebound and even worse, couch or bedbound. I’ve tried to tweak things but they go bad one way or the other almost any time I try.

I’m just fed up. I’m tired. Every day I’m tired. I can’t sleep, I can’t go out, I hardly eat anymore because if I want to go out and do things, I can’t have insulin on board (or very very little, like under a unit). Sure, my a1c went down to 5.7, but my mental health (& probably physical health) has suffered the last few months of pumping. I’ve tried explaining this to my doctor but I guess I don’t express it well enough because she loves seeing my numbers be as good as they are, meanwhile I’m just miserable.


Hi Lauren,

I’m so sorry that you’re having such a hard time. You can use the Tandem pump and turn off CIQ any time you want. Except when I’m on vacation or sick - I had a bout of Covid in January - I only use CIQ in sleep mode overnight. I turn it off in the morning and just watch the CGM and make my own decisions.

I also have a problem of crashing when I walk around or exercise right after a bolus and meal. My solution is to eat only two meals a day and schedule my exercise at least two hours after taking a bolus.

Try not to think of the choice as between forcing yourself to fit the CIQ mold and giving up all of the advantages of a pump. A “dumb pump” served me very well for more than a decade.

If you have the time, health insurance and inclination you might check out the Joslin’s DOIT program in Boston. It’s an outpatient 2-3 day program where you work with a team - including a therapist if required - to put you in a better place with you diabetes.

Good luck and please stick around. There are a lot of nice people here.



While the only official place to use the G6 is your abdomen, I have had wonderful luck using it my arm. The G6 is not perfect, but it is usually very reliable in my case.

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@still_young_at_heart I’ve started turning CIQ off more often and honestly sometimes it gives me more peace of mind knowing that I won’t be given anything just out of nowhere. I do like having it on when I’m out just in case (I tend to keep it in exercise mode at that point) but I find myself turning it off more often than not when at home. I definitely rely on it when it comes to sleeping, though!

The days when I know I’ll be out sometime after breakfast I’ve taken to just eating things like burgers with no buns or something similar that I don’t need to bolus for - I might see a slight rise but I usually walk it off pretty easily.

I’ll look into the program but our insurance is pretty terrible (they don’t even cover my Dexcom, they give us a “discount” price and it isn’t even that good - $377/month!) so I don’t have high hopes of them covering anything like that. Thank you for your suggestions!

@Rphil2 I’ve never worn it on my stomach honestly- I’m a stomach sleeper and I knew I’d never sleep if I wore it there. I started putting it on the front of my bicep because most of the time I don’t have issues there. I can’t wait for the g7 to work with the pump because I hope things improve using it! It’s been a mostly good experience with the g6, I liked how I didn’t have to scan the sensor to see my numbers, but those times when it acts up are certainly frustrating.

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Sounds to me like this is a settings issue. Perhaps reduce your correction factor? I’d definitely do some experimenting!

By “reduce” I mean increase (slightly) the number that one unit changes your glucose by. It will give you less insulin for a given predicted glucose trajectory. Possibly reduce (by a small amount) the insulin to carb ratio?


Mental issues unfortunately are common with diabetes. Our blood sugars can influence our moods, but the day to day of paying attention can really get to us. Easing up on what you think you should do, giving yourself a break from having to pay so much attention can sometimes help. I’ve included a link to a free type 1 online support group at Harold Schnitzer Diabetes Health Center and another link to some helpful videos from Behavioral Diabetes Institute. I hope they can help.

I also recommend you might try “the turn your pump to just a regular pump”. That way you can calibrate your G6, but if it’s off it doesn’t influence dosing unless you want to. Our tech can be wonderful, but can also cause it’s own set of issues. I just had 3 G6 sensors fail in 5 days and it was a very frustrating experience. I finger tested so much my fingers became sore like in the old days. But it also made me realize how much I wanted my tech.

Hugs and I hope you find a happier spot to be in.

@MBW I recently increased my correction factor but after today I did it again just for good measure. I tried messing with my carb ratio & that day didn’t go well (I only reduced it by 1, maybe doing it by a half would make a difference) :sweat_smile: so we tweaked my basal instead.

@Marie20 Thank you! I’ll look at those. I’ve had mental issues long before the diabetes unfortunately so I’m no stranger to anxiety & depression, this has only added to it. I’ve noticed that often when I turn CIQ off I do feel a lot less pressure but I still worry that my basal would be too high sometimes so I find myself checking just in case. It is a little less stressful, though.

I definitely rely on tech at this point! Sometimes I wonder how I was going around injecting & only occasionally checking my blood sugar with a meter! I really wonder how people older than me dealt with it day to day. I’m thankful for what we have now even if it does frustrate me some days.

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In sleep mode it prevents lows but will never give correction bolus. It sounds to me that your serpentines are not correct

It sounds like your correction factor is too high but I go low if I exercise with any insulin on board, even walking and pretty much no matter how high my BG was to start with. I don’t do any physical activity until most of my insulin on board is gone if possible. Try going to sleep mode 24/7. It won’t give you a correction bolus but will still reduce or stop your basal when low. Exercise mode is useless to me because it still gives corrections.


Exercise with exogenous insulin on board is tough! I like to exercise and how can I do it without crashing?

1: reduce my insulin dose if I expect I’ll be exercising after eating

2: have a secondary personal profile, with about 30% of my basal rate, called “Active”

3: take additional fast acting glucose to cover for exercise

4: pay attention to my CGM

Waiting to exercise for a few hours after eating does help.

Of course it’s also useful to know that if I under dosed and my post-mal glucose is trending up I can exercise to stop the climb.

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It certainly is. I know this may not be feasible for everyone, but I find that exercising first thing in the morning (before breakfast/bolus) is the best time to exercise to keep blood sugars from going low. I do this on days that I work from home. In-office days are more difficult…

I believe there’s one fundamental problem and three technical issues here, but they all stem from ignorance. Control IQ is a tool, not a panacea. If you don’t understand how it works what it needs and how to apply it it’s a waste of technology and how to use it,

The “training” that Tandem provides is like familiarizing a student driver with the controls of a car and showing them how to refuel a car. It doesn’t teach rules of the road or develop the skills needed to operate the car while driving it. It assumes knowledge and skills that a medical team should help the user to master, but in my experience, they don’t.

The first issue comes from not understanding what a user and their doctor are responsible for doing -setting up the pump’s software correctly. If that isn’t done right the first time, it’s like expecting a novice driver to handle highway traffic in a car with bent wheels and loose steering. It’s equally life threatening. “Call me if you have problems” just doesn’t cut it.

Control IQ is actually a very simple algorithm. If the doctor/user provides accurate numbers for the users normal state, their ICR, CF and basal rate, provides reasonably close estimates of meal content, and tells Control IQ when the user’s metabolism is changed significantly from normal state by exercize, sleep or illness, strong textthen Control IQ will do exactly what a well-trained cautious doctor or patient would do with that same information.

But if those numbers are not right, then the very simple computer of Control IQ won’t work well. Garbage in, garbage out.

The second issue is not understanding the conditions under which the numbers that Control IQ uses apply.

The “correction factor” commonly used is a single number that applies only when BG is between ~100 mg/dL and 180mg/dL. Once above that range insulin resistance occurs and becomes progressively worse. Below that range carbohydrate absorption becomes impaired.

Similarly, the Insulin to carb ratio is only valid under the conditions where it was measured. When you are more or less active than the average of those condition, then ICR becomes less reliable. Changing meal composition for one meals to include more or less fat and protein changes those conditions.

That means that the user has to be ready and able to intelligently intervene to limit prolonged hyperglycemia and to reverse hypoglycemia whenever Control IQ faithful moron can’t handle changes that produce extremes.

The final issue is a misunderstanding as to how much of a correction Control IQ can provide. If the settings have been made correctly, Control IQ can not cause hypo. It can not prevent hypoglycemia due to grossly excessive insulin onboard no matter the cause. The most it can do is resist trending hypoglycemia from happening.

The maximum correction bolus that Control IQ can provide is limited to 60% of the calculated correction to bring you to the target of 110mg/dL. That correction calculation includes insulin on board, is limited to once per hour and limited to a maximum amount that can be set by the user.

Control IQ can also make corrections by adjusting the basal rate. The maximum basal limit can also be set by the user.

These limits can be found under My Pump/ Personal Profiles/Pump Settings.

I recommend that you buy and study two books: Pumping Insulin and Think Like a Pancreas and go through the Tandem User Guide T Slim X2 Control IQ with that understanding. If you do then you will learn more about the practical application of your insulin pump than your doctor knows.

@Timothy I know this, I’ve used sleep mode many times when not sleeping when I don’t want correction boluses and would rather it just increase basal. But I have no idea what you mean by my serpentines not being correct.

@Firenza yeah I’ve adjusted my correction factor since this post. Using sleep mode 24/7 would be ok but even when actually sleeping I always wake up under 100 so sometimes it would be a little too aggressive for my liking. I do hate that exercise mode even gives corrections - it feels counter-intuitive when you know you’re busy and could easily be bringing your glucose down without needing that bolus. I still use it when out and about because if I didn’t I’d definitely have a hypo.

@MBW I wish I could master the idea of reducing my insulin if I know I’m going to be active. My blood sugars feel so inconsistent even if I eat the same meal that some days I could be in exercise mode all morning after eating without even moving and I don’t spike whereas other mornings with the same meal I’ll go up by 40-50. I know hormones and all that play a part in things, but it makes dosing for activity all the more frustrating for me. I tend to just wait until I don’t have any insulin on board or very little.

@Brianna1 I used to exercise right after breakfast when I was on MDI but now I wake up at 94-106 most mornings. I’d have to eat a little something first and like I stated above, I still haven’t figured out a good amount to prevent a huge spike. I drop just making breakfast in the mornings :woman_facepalming:

@pstud123 my settings were great when I first started months ago. Things have changed since and I’ve been trying to tweak one there here and one thing there as I’ve kept track of how each meal works with my body. I eat almost the same meals every day at this point and still get different results every day. I have plans to read Think like a Pancreas when my library gets it in ebook form, which looks like it will soon. I’ll look at the other book as well.

This may be a hormone problem more than anything else. When did your control destabilize? Can you remember any changes to your cycle? Seasonal changes can have an affect on BG control as well.

I’m sorry you’re having to deal with such fluctuations. I’m glad you posted, though, b/c reading your experience and others’ replies answers a question I’ve had since being diagnosed almost 3 yrs. ago, which is, are my fluctuations normal? Apparently so. It’s exhausting to have to deal with. I used a CGM for 6 months, then quit b/c the numbers were too unreliable and were just increasing my stress even more, from what is already a stressful disease to deal with. Now I do MDI, but I’m home most of the time, so it works better for me.

The other thing I’m still trying to get through my thick skull is, just like others have posted, exercise + correction doses is a recipe for disaster (for me). I can be 230, and if I take even a fraction of a unit of Humalog and then go do a walk up and down some hills, I’ll really drop and go too low. My realization (finally, after too long) is that highs either need exercise, or a correction dose, but not both. If I can’t exercise, I take the correction.

The other thing I’m learning (veeery slowly) is that the correction dose I need is WAY lower than what is recommended by typical advice on managing T1D. Supposedly my correction factor is 100; often I use a factor of 200 or more. In the morning, before I have any short-acting insulin in my body (I use Lantus + Humalog), my correction factor is about 75-100. If I have any Humalog on board, my correction factor is so high it’s laughable. I’ve been burned so many times taking even, say, 1/2 of a unit for a 200 blood sugar 3-4 hours after eating, only to crash one or two hours later.

I really drilled into my head right from the get-go of my diagnosis that blood sugar over 150 is bad, 180 is really bad, and 200 is obscene. So I’ve had this compulsion to correct every time I get these numbers, and way too often have suffered the consequences. I am only now finally starting to get it–my body, despite my best efforts w/ timing, keeping notes, etc., is just going to go “too high” after a lot of (not all) meals, and this usually isn’t due to not enough Humalog, but to the carbs outrunning the insulin for a bit. I just need to calm down and wait for the insulin to catch up (and do some exercises, if I can, but not overdo them to cause a low).

So, a long-winded way of saying that, 1) I feel you, I share your frustrations and experience exasperating fluctuations I can’t make sense of either; 2) going back to MDI helped (it may not for you–no method is ideal, I mean, it is T1D, after all); and 3) it also helped me to be extremely careful about correction doses and really dial them back (lows are really terrible for me, and cause long-lasting pain and muscle strain, so they’re especially to be avoided, in my book).

I hope that helps. :slight_smile: :slight_smile:

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Very helpful details in this reply. As a parent assisting a very young person with initial diagnosis and now going on 30 years as a “helper when needed,” we have seen and heard a lot. Mostly what we’ve seen is the insistent Marketing done by device companies and, sadly, the medical profession, of devices that in the engineering world SHOULD be called Still in Development (or beta-versions). To me it is clear that too much is asked of those with T1DM by suppliers and the blame is placed on the patient instead of the company who markets bad software. In earlier years, as a parent answering really dumb questions from medical professionals, I constructed a List of “The 26 Factors” we take into account for every decision about ratios, exercise… all of it. Also, have read nearly all books. T1DM is HARD to manage. Even the pros in Boston once told me, after SO much data collection and tracking, that “you are not going to find a pattern, ever.” We didn’t stop trying and yet, wow, what a statement to hear.
After inquiries and a lot of reading within peer-reviewed journals, my conclusion is that it is Not the patient. It is the device makers. CIQ – a misnomer. Also, I do agree that patients do need to deeply educate themselves for very good reasons, and also because medical professionals do not have time. Thank you, this is an excellent forum

@Firenza We went on a trip to Disney in October when I needed to reduce my basal to .6/hr and go almost 24/7 in exercise mode and it worked pretty well except for a few times when I dipped and the last day was a disaster due to a changed sensor (it was awful). I lost 10 pounds on that trip so I was certain soon I’d probably need adjusting but I went back to my normal .9/hr and was fine until a little after Thanksgiving when I had a bad low not long after eating lunch. I started dosing for net carbs instead of total carbs after that and things sort of went back to normal, but not always. I had another bad low in December around Christmas and tried to adjust things soon after with my basal but it didn’t seem to work at the time. The only “consistent” thing I notice is at the beginning of my menstrual cycle I need far less insulin in the morning. I spend the whole morning after breakfast in exercise mode and I could still only “spike” by 10 points.

@BKN480 I’m glad to hear someone else has the same experience even though I’m sorry you’ve also had to go through it, it’s truly exhausting. I was on MDI previously and only switched to a pump because I was bouncing between 300 and 95 (mostly because I was trying to adjust things on my own and my doctor didn’t want me to adjust despite losing weight and needing some help) I know for certain that my correction factor needs to be way higher than my doctor set it for me at first.
I’m at home almost all the time and I don’t work (haven’t since 2020) and the only reason I don’t right now is because of all of this. There is no way I could return to what I did before without having to constantly pop glucose tablets. I never gave any correction doses when I was on MDI, either, so getting them automatically threw me off. I knew it would happen with CIQ but it didn’t help things.

@Boston I realize there are very few patterns in T1D - once you get something down it changes. I did so much research on the different pumps I was looking at before making a decision. I watched so many videos and read articles. I was the most educated person the Tandem trainer/rep had dealt with that she barely had to help me. It’s always comforting to hear that others deal with the same issues despite how educated you are on the subject.

I think you missed the points I was trying to make. Control IQ is a tool. It’s reliable and not very complicated. When you have a chronic illness it’s not a matter of what a doctor expects from you it’s a matter of what you expect from yourself and what you are able to do.

You can’t find meaningful patterns in any complex system that is totally uncontrolled. Systems we build are created starting with very simple systems and carefully adding on to them. Unfamiliar complex systems are analyzed by controlling as many variables as possible and observing how a few control variables result in changes. This are the bases of engineering and, its child, science. ( If you believe the relationship is the opposite you haven’t studied history.)

Although it seems very complicated managing blood glucose effectively requires only two things; Understanding a person’s rate of metabolism and controlling their actions. Any person who does not control his actions in a way where they stay within their ability to keep themself safe, whether or not they have a chronic illness, is a person who will get in trouble.

A rational person with type 1 diabetes will recognize that they have a life-threatening condition and will make a commitment to keeping themselves safe by learning as much as they can about how their body responds to food, insulin, activity, stress and illness.

What this requires is periodically denying their impulses and living on a controlled regimen and keeping sufficiently detailed records so that they can assess how their body may have changed.

The latter used to be very difficult before CGMs. Today it can be done simply and automatically IF an insulin pump is not complicating things by working in automatic mode at the time.

imo In general Control IQ should not be enabled until it can be configured to match the individual’s metabolism. I believe that this is being done because those setting up the system mistakenly believe that it’s an artificial pancreas. It’s not marketed as such because it is not. No company would give their product an overly complicated name like hybrid closed loop insulin pump if they could call it an artificial pancreas.

Instead it’s a tool that can do what a person who understands what he’s doing would do, 280 times a day instead of four or eight. That can make it possible to get much finer control of BG at any time of the day. It’s not a comprehensive solution and it’s not a perfect solution. It’s better than trying to do that manually.

If a person knows enough about using insulin to make intelligent decisions about using sliding scale then Control IQ can make this job simpler. If they don’t then Control IQ is going to make things harder to understand.

The better you understand what ideally should be done, the more accurately you can provide information to CIQ, the better the job that you can do with it ,and the easier the job of managing BG becomes.

So starting with Control IQ is the most difficult part of using it, but objectively it is not difficult. What it requires is realistic expectations and a systematic study of how your body responds to food and insulin which can be done by anyone. All it requires is eliminating variables.

The book Think like a Pancreas describes the very simple process of systematically monitoring how your body behaves, one meal period at a time. If followed for a week for one meal you can determine your basal rate for that period. If done for all three meal periods and sleep, you will learn your 24 hour basal profile.

The nightime pattern observed during the dinner study from a week’s sleep data will also show if and when dawn phenomenon starts. (Good sleep and good fasting BG makes everything easier, so I advise that dinner response be studied first.)

After basal profile for the entire day has been determined over the course of a month, if you’re willing to eat the same thing every day for one meal for a week you can accurately determine your insulin to carb ratio for that meal. With those two factors determined a person who is committed to achieving control should be able to get fairly good control of their blood glucose using Control IQ for that meal and period.

This sounds more complicated than it actually is. Mostly it’s just boring. Breaking that boredom by studying one meal at a time provides a series of rewarding improvements instead of continual frustration. Reinforcing knowledge and behavior through rewards is the basis of successful education.

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Hi, excellent input. Thank you.
Although, I did not miss the point ~~ I understand a lot about T1 and technology/engineering. It’s just so exhausting to keep doing the drill-down with every new technology and the human factors (which are egregiously ignored in device engineering).

I look at the T:slim X2 with Control IQ as being analogous to the iPhone 3. As an engineer I know that the state of the products is juvenile, but rather than curse Tandem or the product as being less than what I know is technically possible, I’ll use it as best as I can.