International Consensus on Time in Range

Diabetes Technology Glucose Monitoring
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In conjunction with the American Diabetes Association Scientific Sessions conference held in San Francisco earlier this month (June 2019), the ADA released online an ahead-of-print summary (June 8, 2019) regarding using continuous glucose monitor or CGM data to affect better outcomes for people with diabetes.

Here’s the introduction from the summary.

Improvements in sensor accuracy, greater convenience and ease of use, and expanding reimbursement have led to growing adoption of continuous glucose monitoring (CGM). However, successful utilization of CGM technology in routine clinical practice remains relatively low. This may be due in part to the lack of clear and agreed-upon glycemic targets that both diabetes teams and people with diabetes can work toward. Although unified recommendations for use of key CGM metrics have been established in three separate peer-reviewed articles, formal adoption by diabetes professional organizations and guidance in the practical application of these metrics in clinical practice have been lacking. In February 2019, the Advanced Technologies & Treatments for Diabetes (ATTD) Congress convened an international panel of physicians, researchers, and individuals with diabetes who are expert in CGM technologies to address this issue. This article summarizes the ATTD consensus recommendations for relevant aspects of CGM data utilization and reporting among the various diabetes populations.

I’ve long been a proponent of using diabetes data to guide and inform the tactics I use to rein in the inherent metabolic chaos that is diabetes. I realize that my interest in data is not shared with all people in our community but my experience and success convinces me that it’s a worthwhile resource.

I regularly monitor my Dexcom CGM data and will often examine the 14-day Ambulatory Glucose Profile (AGP) report found within the Dexcom Clarity software. The AGP helps me make adjustments to my insulin to carb ratios (I:C) and insulin sensitivity factors (ISF).

As Sugar Surfing’s Stephen Ponder reminds us, diabetes is a dynamic disease. It changes all the time and this is what makes managing it so difficult. Managing diabetes with a static mindset will test your sanity! Once a person with diabetes accepts this reality, you can develop ways to manage this moving target.

One fundamental personal truth I hold is that merely watching data on a regular basis will subconsciously increase my motivation to improve that data. Not sure if this works for everyone but it certainly does for me.

The whole report is worth reading but there are a few things that caught my eye. The consensus for this group set the glucose limits for the time in range statistic at 70-180 mg/dL (3.9-10 mmol/L) for people with type 1 and type 2 diabetes.

Interestingly, this panel chose lower, more aggressive targets, for diabetes management during pregnancy. For this cohort the consensus set glycemic targets at 63-140 mg/dL (3.5-7.8 mmol/L). I find this of interest since I set my targets at 65-140 mg/dL (3.6-7.8 mmol/L). I do not become hypo symptomatic until I reach 65 mg/dL (3.6), so I use that as my personalized lower limit.

The report noted that personalizing this target range is appropriate.

It was agreed that CGM-based glycemic targets must be personalized to meet the needs of each individual with diabetes.

Many of you know about my recent discovery of the effects on the A1c number of iron deficiency anemia. I puzzled for many years wondering why my A1c number consistently floated about 0.5% above the number predicted by my CGM data. I questioned several endocrinologists about why this was happening and heard no answers.

It wasn’t until recently, when I discovered that the iron levels in my blood were low, that I put 2 and 2 together and realize that that was the reason for my skewed A1c. This report also noted that the A1c did not correspond accurately with glycemic exposure for all people with diabetes. Once I started to supplement with iron, my A1c measured within 0.1% of the CGM predicted number.

Moreover, certain conditions such as anemia (37), hemoglobinopathies (38), iron deficiency (39), and pregnancy (40) can confound A1C measurements. Importantly, as reported by Beck et al. (41), the A1C test can fail at times to accurately reflect mean glucose even when none of those conditions are present.

Even given these A1c/glycemic exposure discordances, the group affirmed the importance of the A1c number and sees CGM data as a strong complement that people with diabetes can use to increase their positive health outcomes.

Finally the consensus report makes this conclusion.

This information allows people with diabetes to optimize dietary intake and exercise, make informed therapy decisions regarding mealtime and correction of insulin dosing, and, importantly, react immediately and appropriately to mitigate or prevent acute glycemic events (87–89).

I wholeheartedly agree with this and hope that clinical practitioners make an effort to understand these metrics and help persuade their patients about the utility of this data.

If you want to take your management of diabetes using a CGM beyond the realtime benefit of out-of-range alarms, you may want to consider the ideas presented in this paper. My attention to this data detail greatly improves my quality of life and keeps metabolic mayhem at a minimum.

What do you think?

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Thanks Terry, I found the paper very informative. Here is another link:
Clinical Targets for Continuous Glucose Monitoring Data Interpretation: Recommendations FromtheInternationalConsensus on Time in Range

I would have liked to see more discussion of the “Older” TIR goals (copied below from Figure 1)…the paper does not elaborate on these but is pretty general: “Older and/or high-risk individuals with diabetes are at notably higher risk for severe hypoglycemia due to age, duration of diabetes, duration of insulin therapy, and greater prevalence of hypoglycemia unawareness.” I am 62 years old and would not enjoy living with the elderly TIR…above 180 mg/dl for 50% of the time. I plan to ignore those “Older” goals for many more years.
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Me, too. I imagine what the authors had in mind were elderly people no longer capable of monitoring and making effective treatment decisions. People who live in nursing homes and at the mercy of paid caregivers is likely what the writers of this advice had in mind.

Unambitious goals do not motivate me. This document is intended to cover a wide spectrum of people with diabetes. They’re more driven by the safety concerns of the people on the edge of our demographic and as a result, they fail to address more capable older people like us.

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Its interesting that pregnancy affects accuracy of the hba1c. Recently, I’ve been having a lot of problems with my dexcom that I never had before. It keeps having sensor issues which it never had before. I had 4 days out of the last 30 where my time in range was less than 70 percent because I just wasn’t getting readings for hours at a time, which never used to happen. I said to my husband last week that I wondered if the pregnancy hormones had something to do with all these problems. I guess if pregnancy affects the hba1c reading, it could also affect the cgm. It’s frustrating because I want the surety of constant readings more now, but I guess it is what it is. My glucometer is getting a lot of use again, so I guess I should just hope that that is accurate.

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I have a strong feeling we are a little more obsessive about our numbers than the general population? It also helps being able to share information with each other.

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Maybe I will follow those rules in another 15 to 20 yrs. I am 68 now. Of course I am assuming that I won’t be in a nursing home, but one never knows.

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A nursing home is scary right? But maybe at that point I wouldn’t care as much!

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I found the same with my Medtronic CGM when I was pregnant, but the Freestyle Libre seemed to work well. I relied more on that (even though at the time it wasn’t even available in the US and I had a friend send them to me from abroad), but mostly just did a whole lot of finger sticks.

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Medtronic CGM never worked for me. I tried several times over several years, but it was just completely useless. I was both surprised and happy when the dexcom worked, and it still works about 90 percent of the time, but I need to double check more often and have more blackout periods than when not pregnant. Also, sometimes the pregnancy hormones throw things off so badly that I think, “that can’t possibly be right, the CGM must be having problems” and then I test and the CGM is totally accurate but my body is just being crazy. I’m still doing less fingersticks than I did before I got the CGM, so I’m still very grateful to have it.

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John 58 and Terry, very useful information in your comments. My daughter is 9 years old and is totally asymptomatic, but with diligence and hard work we are achieving 80% + in range for the last 3 months. Hypos less than 0.8%

My question to you both, and it may not be appropriate to ask here, would you encourage us to move to a pump? I don’t see data suggesting we will achieve greater than what we do now with a pump but with our carb-counting, exercise regime and dietary control I see some people in the US are achieving 97% + on a pump system.

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Congrats on your high % time in range with very low hypo %.

I see the pump as just another tool. I don’t consider it as essentially a way to get better performance. Many people who use multiple daily injections can get equivalent performance.

I think the more critical skills that lead to better numbers are knowledge, willingness to do personal experimentation, and persistence than a pump in and of itself.

My low-carb, high-fat way of eating, for example, plays a more significant role in my numeric data than the pump itself. The pump does improve my quality of life, however, in that it can reliably remember when I took my last dose. The pump also makes meal insulin dosing more convenient in social settings and we tend to eat in social situations.

There’s also the need to involve your daughter’s preferences. She may not like the idea of dealing with managing this cyborg device when she just wants to blend in with her peers.

In short, the pump itself does not directly deliver better performance. To get the most out of it, the person wearing it must combine its use with other tactics like low carb eating and consistent prebolusing to achieve stellar numbers like 97% TIR. My best performance tops out in the low 90s and I also use an automated insulin dosing system. Getting involved with a pump now may set up your daughter well for transitioning to an automated insulin dosing system in the future.

Your numbers are very good at this time but you didn’t show your target range. A decision to use a pump is a subjective one that each person or family needs to consider. Good luck going forward.

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