The State of T1D Outcomes published


Last Tuesday, the T1D Exchange Clinic Network published a must-read seven-page paper, “State of Type 1 Diabetes Management and Outcomes from the T1D Exchange in 2016–2018” in Diabetes Technology & Therapeutics (Foster, Beck, et al.,) – including a treasure trove of supplemental data. Like the previous data ( Diabetes Care 2015 , JCEM 2012 ), these updated T1D Exchange Registry outcomes are concerning, showing no improvement in A1c outcomes in the past five years, including a worsening in young adults. Moreover, these remain a best-case scenario for the US, since they occur at the best US centers and most people (74%) have private health insurance; real-world, average outcomes in the US are likely worse than these already-grim data, though the “best” centers may also see tougher, more complicated patients.

This paper serves as a major reminder for the field: far more work is needed to move population-level outcomes in type 1 diabetes in the US. CGM use is rising nicely, but remains used by a minority of people with type 1 overall – even at the top clinics. Leveling the playing field on outcomes still demands breakthrough innovation coupled with strong access – to drugs, to devices, to automation and decision support, to engaging education, to insightful data, to healthy food, and to meaningful familial and other support.

  • Registry data was collected between January 1, 2016-March 31, 2018 (n=22,697), comparing diabetes management/outcomes to similar data collected in 2010-2012 (n=25,529). In 2016-2018, participants spanned from 1-93 years, with 74% on private health insurance and 49% (n=10,249) classified as overweight or obese – a reminder that weight loss also remains a critical need in the type 1 population.

A1c – No Change in Adults, Worsening in Young Adults

  • In the latest T1D Exchange data, only 21% of type 1 adults met an A1c goal of <7%; only 17% of youth met an A1c goal of <7.5%. Overall, the adjusted mean A1c was 7.8% in 2010-2012 and rose to 8.4% in 2016-2018 (p<0.001) – this was mostly driven by worse outcomes in adolescents/young adults. The chart below compares mean A1c levels by age, with orange representing previous 2010-2012 data and blue representing 2016-2018 data. The hump is a big concern – mean A1c during childhood was ~8.1% at 5 years of age, peaks at ~9.3% between ages 15-18, and decreases down to 8.0% by age 28. Beyond age 30, mean A1c remained fairly steady around 7.5%-7.9%. The paper’s conclusion is clear: “there is no indication from these data that HbA1c levels in the registry as a whole have improved over this 5-year period despite an increase in the use of insulin pumps and CGM.” Unfortunately, these concerning data are probably a best-case scenario – these are the best US centers! In the general population – especially those getting care in primary care – outcomes may be even worse than these registry data. Racial and socioeconomic differences also continue to exist in A1c levels, as shown in Supplementary Table S5.

Average A1c by year of age: 2016-2018 (blue) vs. 2010-2012 (orange)

  • CGM users have lower A1c levels, with fairly minimal differences between pump+CGM vs. MDI+CGM. The chart below plots mean A1c by technology use in the new 2016-2018 data set – MDI+fingersticks (solid black), pump+fingersticks (horizontal stripes), MDI+CGM (solid white), and pump+CGM (diagonal stripes). The one advantage for CGM users on pumps was in adolescents – note the middle bars below, where mean A1c was ~0.5% lower in CGM/pump users vs. CGM/MDI users. Dexcom has shared these data at numerous conferences, emphasizing that CGM confers clear, consistent A1c benefits regardless of insulin delivery method. This offers a clear opportunity for both sides of the field – smart pens/decision support should add further value to current MDI+CGM, and pumps+CGM with automation will add further value over what non-automated systems offer now.

CGM Use – Quadruples to 30% of Participants, >10X Pediatric Gain

  • CGM use has increased from 7% in 2010–2012 to 30% in the 2016-2018 dataset, including a >10x rise in children <12 years old – from 4% to 51% use in <6 years and 3% to 37% in 6-12 years! Since the full 2016-2018 data was collected over a wide time span (depending on when the questionnaire was filled out), there is a separate plot with the subgroup of data collected in each year – as of 2018, CGM stood at 38% penetration in the Exchange, up from 31% in 2017 and 24% in 2016. This impressive uptick (especially from a higher base) parallels the rise in sales in the field. In line with prior exchange updates, Dexcom has a dominant share of the Exchange, with 77% penetration in 2016-2018. We expect growth to continue or possibly even accelerate further given product innovation and an expanded field.
  • Overall, the clear message is that CGM still has enormous runway in the US – it is still not at a majority of users at the best US centers. Paired with the A1c data, there is clearly huge room to drive better outcomes with CGM – obviously, real-time glucose data is a tool, not a therapy, and we look forward to decision support/automation helping to safely reduce hyperglycemia.

Figure (A) CGM use over time and (B) CGM use in 2010-2012 (white) vs. 2016-2018 (black). CGM was used in 7% of people overall in 2010-2012 vs. 30% in 2016-2018.


  • Mean fingersticks per day were 4.1 in 2016-2018 (down from 4.7 in 2010-2012), with a sizeable 41% reporting 0-3 fingersticks/day . Even if we assume 0-3 fingersticks/day is the case for every CGM user in the Exchange (30%), that means a full one in nine type 1’s (11%) at the best US centers are checking their blood sugar 0-3 times per day! We’d love to see more granularity on the 0-3 – how many are taking one fingerstick per day or none? How many are on CGM? We cannot imagine anyone being anywhere close to standard of care if they are not on CGM and using zero or one strip a day. If those with zero checking could become a greater focus, likely those patients who are generating the most spending may see improved outcomes – this would be a big deal in such a high-risk population.

Pump Use – Slight Increase, Used by a Majority (63%) of Participants

  • Insulin pump use increased from 57% in 2010-2012 to 63% in 2016-2018,with the largest increases in children (50% to 60% in children <6 years old and 58% to 68% in children 6-12 years old). Obviously this highly over-reports true pump penetration in type 1 in the US, which is still mostly assumed to be around 30%-35%. Without all companies reporting, however, this is an estimate.
  • In 2016-2018, 53% of pumpers were on a Medtronic pump, followed by 18% for Insulet, 18% on Animas, and 12% on Tandem. Obviously those have probably changed quite a lot in the latter half of 2018, given Animas’ exit, Medtronic’s upgrade programs, and strong years for both Insulet and Tandem.

Severe Hypoglycemia – 1 in 10 in Older Adults Had An Episode in the Past Three Months

  • In 2016-2018, 6% of T1D Exchange participants reported a seizure or loss of consciousness due to hypoglycemia in the three months before questionnaire completion ; this ranged from 5% in participants <18 years to 10% in participants >50 years old. The latter is obviously very, very concerning – 1 in 10 is unacceptably high! So is the low end of the estimates, at 5%. Insulin pump use was associated with lower frequency of experiencing a severe hypoglycemia event (5% vs. 9%; p<0.001), and CGM use trended toward a lower severe hypoglycemia frequency (5% vs. 7%; p=0.06). Although CGM users would be expected to have a lower severe hypoglycemia frequency than non-users, the difference was “relatively small,” potentially reflecting selection bias – i.e., CGM may have been prescribed or used because of frequent severe hypoglycemia in the first place.
  • As data have continued to demonstrate, the frequency of severe hypoglycemia in the T1D Exchange was not associated with A1c level – running with a high blood sugar all the time does not protect against severe lows.

DKA – Affected 4% of Participants <26 Years, Less Likely with Pump or CGM

  • At least one DKA event in the three months before the questionnaire was reported by 3% of participants, with the highest frequency (4%) in participants <26 years old . Participants using an insulin pump were less likely to report experiencing a DKA event than participants using injections (2% vs. 4%; p=0.002). Similarly, participants using CGM had fewer DKA events than non-CGM users (1% vs. 3%; p=0.04). Participants with higher A1c were more likely to experience a DKA event than participants with lower A1c
    • Only ~20% of registry members reported having a blood ketone meter . This is not necessarily overly surprising, but concerning in light of potential for more widespread use of SGLT inhibits in type 1 diabetes. Read our detailed reporton the FDA Ad Comm for Sanofi/Lexicon’s sotagliflozin for more details. Presumably even fewer know how to interpret a ketone meter’s results.

Additional Findings of Note

  • Racial and socioeconomic differences are pronounced, especially in use of devices. For instance, at pretty much every age and every race, those with incomes >$75,000 have double the use of CGM vs. those with incomes <$50,000. The largest difference is in the Hispanic/Latino community, where there is a 3x difference in CGM use between high and low incomes – i.e., 16% CGM use in lower incomes vs. 51% use for higher incomes (adults >26 years). See all the data in Supplementary Table S3. Notably, the gaps are smaller for pumps, perhaps reflecting more established reimbursement or simply more awareness.
  • Across the board, use of non-insulin medications remains uncommon, with metformin the highest at 6% use in adults (>26 years). It is important to note that 49% of the participants in the 2016-2018 were overweight/affected by obesity, meaning there is huge potential for SGLTs and GLP-1s to help. SGLT-2s and GLP-1s were used by 1% of the panel each, translating to n=232 and n=500 users out of 22,297 participants. See the complete breakdown of non-insulin medication use in supplementary table S1. We’ve heard an estimate that 50,000 people with type 1 diabetes are on SGLT-2 inhibitors off-label, which sounds too high – on a base of 1.5 million type 1s that’s 3% usage, and the Exchange presumably oversamples for early adopters.
  • Most participants reported never downloading blood glucose meters, CGM devices, or insulin pumps at home. Other than using Dexcom Share (the most popular mobile app, by far), use of apps was also very uncommon. See the complete data in Supplementary table S4.

Close Concerns’ Questions

Q: What will it take to drive population-level improvements in A1c in type 1 diabetes? How much value will automated insulin delivery add – both for pumps and injections?

Q: What is driving the adolescent/teen worsening in A1c levels? How much of a role is lack of sleep playing? (Stay tuned for Adam’s upcoming diaTribe column on Why We Sleep , which specifically addresses this issue of sleep in teens.)

Q: How does type of insulin used impact average A1cs? What percentage use “next generation” insulins like Toujeo or Tresiba or Fiasp and how do their A1cs look? What about those using off-label “adjunctive” therapy (SGLTs, GLP-1) or those using old insulins like NPH and Regular?

Q: Where are PROs routinely collected and what do those show (measures of emotional well-being or other measures showing familial stability or lack thereof)?

Q: What can be learned from Bright Spots: the sub-group of patients with A1c <7% or <6.5% without severe hypoglycemia? What are they doing that could be replicated?

Q: How do A1c levels compare between different nutritional approaches to type 1 – e.g., low-carb vs. moderate carb vs. high-carb?

Q: How much variability is there between T1D Exchange clinics? What can be learned from Bright Spot clinics with a large percentage of type 1s at an A1c <7%?

Q: What is average time-in-range across CGM users in the T1D Exchange?

Q: How do T1D Exchange outcomes compare to the general type 1 population – i.e., how much is the registry data better-than-average?

Q: How much of CGM adoption is still gated by awareness vs. access vs. perceptions’ of the technology? What will unlock the market? Could we see adoption cross 50%-60% in the next three years? How is education of CGM rated overall and how are HCPs scoring on this front?

–by Adam Brown and Kelly Close


As someone who lives with and enjoys the benefit of a sub 6% A1c without undue hypoglycemia, I continue to be astounded that my doctors and clinicians in general incuriosity about people like me. I am not a minority of one. Just check out the TypeOneGrit group, whose children almost all live below 6% A1c and many below 5% A1c.

How do all the professional medical associations, like the ADA, AACE, AADE, and JDRF, continue to ignore and discount the tactics employed by the more successful segments of the population with diabetes?

Why have they not taken more of an interest in using carb-limts, sugar surfing, and other active management techniques? I suspect that their adherence to the status quo damages the overall outcomes of people with diabetes.

When will our medical advocates catch up to the understanding and performance found in this small yet successful group?


I think they weigh their recommendations against what they think the average person can adhere to. Some people have the energy and self discipline to more tightly control their sugar.

Personally I limit carbs and use walks to lower blood sugar. Obviously I still take insulin but if a walk will work I use that before insulin for post meal spikes.


How about studying me? Type 1 for 60 yrs. No A1c over 5.5 for over 20 yrs. No neuropathy, retinopathy, gastroparesis.
I have had heart stents for 10 yrs. Why? High LDL, 22 yrs of urine testing, A1c of 10 when that test became available, grandfather who died of a heart attack? I don’t have a clue.

Good genetics? Maybe, although I did get a bit of retinopathy when I was 30, but it cleared up after I got a good handle on my A1c. I know that Dr. Bernstein had many problems before he really reduced his A1c.

I have had doctors lecture me for having low A1c’s. The faulty Accord study was just making the rounds, and the docs I spoke with said that my A1c must be 6.5. I ignored their advice.

I absolutely know that my low A1c is keeping me healthy. Yes, it is a lot of work, but I am worth it.

I wish all diabetics could be told that very good health and a low A1c is very possible. Even without a pump and a CGM


This just drives home the point, of how UNUSUALLY WELL CONTROLLED and SELF-SELECTED tudiabetes participants are.

You might think from reading posts to tudiabetes, that most T1’s have A1C’s under 6.0 and almost all are under 7.0.

But in a broader study of T1’s, only 21% are under 7%.

While being part of the “self-selected elite good control T1’s” myself, I don’t think the majority of discussion on tudiabetes does a good job representing diabetics and their challenges as a whole.


Totally agree, though putting it that way makes it sound like being more representative is something we are responsible for. The key term is “self-selected.” You have to actually care about your D management to arrive at a site like this to begin with, and there’s not a whole lot we can do about people who don’t. OTOH, hopefully one effect for the people who come here who aren’t doing so well is that they find information they need to do better, and so they start being part of the self-selected elite themselves.


I used to get that back when I was on R/N and later basal-bolus MDI, the theory being that since A1C is an average, you have to be having a lot of hypos to get it any lower than that. I think that theory had considerable validity for R/N, somewhat less for basal-bolus MDI, and much less when you add CGM to the equation (I think the study is correct when it indicates “fairly minimal differences between pump+CGM vs. MDI+CGM”).


I agree Chris, I think the key is self discipline. Although I spend an hour a day at the gym now, previously I had Chronic Fatigue Syndrome for close to 5 yrs, and at times, I couldn’t walk across a room. My A1c then was 5.1. Exercise was not a factor in treating my diabetes, but self discipine was crucial.


I realize that T1Ds who actively participate in the diabetes online community are not representative of the larger T1D population. What the original post says is that T1Ds, as measured by A1c, are performing worse in controlling their diabetes in the more recent period than in the past one.

My point is that the current standard of care is not doing a very good job for the T1D population. I go back to my earlier point. If the current treatment efforts are not measuring up, why do clinicians and their professional organizations show so little interest in the portion of this population who are living with much better A1c numbers?

Are we simply dismissed as anecdotal outliers or are significantly different in some genetic way that we cannot even be considered as a source of at least part of the solution? I think we, as a group (20% is a significant statistic) have collectively identified tactics and values that have stood the test of time.


Did you ever see the episode of ThE Office where the bosses call Michael to NYC for a meeting and ask him for his secret, how his branch is doing so well while all the other branches are suffering in the down economy. And Michael just blabbers on and has no idea.

I would do the same as Michael if I was asked my secret for getting good A1C’s. I have no idea how I consistently turn in A1C’s in the high 5’s and have only had a couple ER trips for hypos in the past 30 years. If you asked me what I was doing right I would just blabber some trite junk while at the same time knowing that I almost always struggle mightily against bgs that often careen high to low and back again with little rhyme or reason.


Excellent post, @Mila. Thanks for all the wonderful research of late!


2 years ago I was one of the 80% with a higher A1C. I was sick and tired from all of the high BG’s but couldn’t figure out what had gone wrong in that last couple of years after having gained decent control as a teenager. I made radical changes to my diet but didn’t achieve better control. It took changing all of my insulins to finally break through and with enough Afrezza I can eat whatever I want and still maintain a low A1C and high time in range. Unfortunately due to cost I haven’t had enough access to Afrezza to eat as I would like so low carb it is until I can get insurance to approve it (hopefully next month).

I think the biggest factor for most people with gaining tight control is access to the best medications/technology and the knowledge on how to use the tools with diet and exercise. I see so many people online who get a Dexcom and then set the alarms to 300 or some other high number like that and think, “what good is doing you way up there”? So many people don’t get enough education to actually take care of themselves when they are diagnosed unless you were diagnosed at a children’s hospital, but in those cases the parents are getting most of that education and when the kids start to take over as teenagers they can flounder if the knowledge wasn’t properly passed down.


The thing is, this site helps with gaining knowledge of how to deal with situations and the fact that there is someone out there that has usually run into the same situations and is willing to share that knowledge. You just don’t get that in general, that experience, from someone that doesn’t have type 1.

Plus the doctors, seem to get really nervous when you have lows, even if you’ve not needed help or not passed out, just went lower. The new endo didn’t like I had my BG aim at 95 during the day. I was asked isn’t that too low. I think they want to see the lower A1C but would love to see this even keel 120-130 all the time, all day. Think about it, if I hadn’t had originally a type 1 endo, if I hadn’t been on this site to know others aim for a lower number, I would have only my new endo telling me 95 is too low of a number to aim for.

But in general I think people on this forum are more proactive than the general population and can get input more easily from others.

Thanks for the information Mila!


After thinking more about this issue, I realized that a few significant attempts have been made by the medical establishment to measure the performance of well-motivated and controlled people with T1D.

The American Academy of Pediatrics studied the glycemic control of the Facebook group, Type One Grit. This 2018 study produced some amazing findings.

The mean HbA1c of participants following this low carb diet was 5.67%. A whooping 97% of participants achieved the ADA glycemic targets, which is amazing — on average, only 14% of people between 18 and 25 with Type 1 diabetes meet ADA glycemic targets, and 30% of older adults reach this target. The mean daily insulin dose was .40 U/kg per day. And even though these people were eating a low-carb diet, the rates of severe hypoglycemia were relatively low — 2% reported seizure or coma due to hypoglycemia.

Another interesting piece was how the participants felt about their health and their healthcare on this low-carb diet. Although they reported high levels of overall health and satisfaction with their diabetes management, they did not feel similarly positive about their healthcare providers. Many (27%) were hesitant to discuss their diet with their diabetes healthcare providers, and of those that did tell their doctors or endos about their low-carb diet, only 49% felt their providers were supportive.

Another effort to study the glycemic control of people using the do-it-yourself automated insulin dosing system, Loop, is likely measuring the performance of motivated and pro-active T1Ds. The Jaeb Center for Health Research is conducting the study. Here’s the program description.

What is the Loop Observational study?

The study is being done in collaboration with Loop developers to collect information from adults and children with type 1 diabetes using Loop. It is being paid for by the Helmsley Charitable Trust. The purpose of the study is to collect information from 300 – 1000 adults and children with T1D using Loop in the United States. This information will be used to learn more about how well Loop works, what problems users have, how often severe hypoglycemia and diabetic ketoacidosis occur, and how well the system controls blood sugar levels.

I enrolled in this study recently and I should have raised this point earlier in the thread. In any case, I believe that this study will provide enough data to persuade clinicians about the effectiveness of Loop in aggressively controlling blood glucose while maximizing time in range and minimizing hypoglycemia. This study will last about a year.

These two studies, unfortunately, are an infrequent exception to the general lack of interest by mainstream medicine in the higher performing segment of T1Ds. I hope these studies portend a change that will be sustained.


I read a news article this morning about a young man who was rationing his insulin which is just so sad. The article said that type 1 diabetics should aim for a glucose level of 120 to 130. I silently yelled at my iPad. What misinformed information.


If you have to give advice to everyone saying 120-130 seems reasonable. Telling everyone to aspire for 90-100 is likely to get people killed. Only those who are really on top of things should be attempting that level of control.

I also think setting lower targets causes some to give up or decide its unattainable and not even try.

We have to remember the problem isn’t the ADA setting a A1C goal of < 7. The problem is the majority are not hitting that goal. It’s probably not helpful to tell all those people they are doing an even worse job than they thought setting a target < 6.


I do think telling someone to aim for something way out of range of what they’re at, can make it harder for some people. Baby steps sometimes? But knowing it’s okay to aim for lower levels seems reasonable. I don’t think I will ever try to aim for under 6 A1C, my morning spike alone makes that a problem for me. I’m 6.4 A1C and happy with that.

The US ADA for type 1’s does have lower end recommendations starting at 72 being okay before meals for stricter control guidelines. The UK NICE recommends it for all type 1 diabetics as their lower end before meals. The top end numbers vary between countries with the UK’s being stricter.

I would never aim for 72 as I have always gotten shaky below 75. I know you get used to it the more if you are lower, I’m just not sure I want to.


I don’t think it said A1c was worse, just that it hadn’t improved (except in adolescents, where it had worsened).

I think this is a very complex issue that has multiple facets. Some don’t have the education to achieve tight control. Some don’t have the resources (both material and mental) to achieve tight control. Some don’t have the motivation to achieve tight control. Some may genuinely be unable to achieve tight control despite having the education, resources, and motivation to put forth the best attempts. For many, more than one of these factors affects them. We all live very complicated and diverse lives, and the answer is rarely simple nor of a single origin.


You’re right. With all the health issues I must now manage, I am blessed with good cognitive function and a resilient attitude. It’s a gift that can’t be presumed for some slice of T1Ds. But I think there is still a significant portion of people who could do better.

I agree with your complexity point. And your big heart – thanks for the comment.


Wow! You are what Dr B would call a ‘survivor’! Impressive :smile: