While the study didn’t report the number of weekly excursions, it’s probably safe to assume, given the averages, that I believe there’s plenty of room for improvement in the vast majority of the participants. We never want to see glucose above 140 mg/dL. The target I want my patients to hit in terms of the number of total glucose excursions above 140 mg/dL per week is zero. Spending 30 minutes a day with glucose levels above 140 mg/dL may be the benchmark in this population, but that does not mean it’s optimal. Almost one-third of the participants had at least one hypoglycemic event, defined as a glucose level below 54 mg/dL, and almost half had at least one hyperglycemic event, defined as a glucose level above 180 mg/dL. Median time spent with glucose levels above 140 mg/dL was 30 minutes a day and median time spent with glucose levels below 70 mg/dL was 15 minutes a day. This study was used to support the argument that there is in fact tight glucose control in these individuals, confirming that “normal is normal is normal,” as one of the study’s coauthors put it.Ī closer look at the findings, however, suggests otherwise. Severe glucose variability was present in one-quarter of normoglycemic individuals, with glucose levels reaching prediabetic ranges - defined as values greater than 140 mg/dL - up to 15% of the duration of CGM recordings, suggesting glucose dysregulation is more prevalent than we might think.īut the recent JAMA perspective pointed to a 2019 study that was attempting to create reference ranges for glycemic profiles in more than 150 healthy nondiabetics that found they spent 96% of the time between 70 and 140 mg/dL based on about one week of CGM data, on average. In 2018, a study in nearly 60 participants found many individuals considered nondiabetic by standard measures showed high glucose variability determined by CGM. In other words, in non-diabetics, a fasting morning blood glucose level of 90 vs 95 vs 100 vs 105 mg/dL can have much more to do with the previous night’s dinner, the quality of sleep that evening, or even the speed and suddenness with which they woke up that morning (and the concomitant cortisol surge) than their true health. Furthermore, we’ve seen how irrelevant morning fasting glucose can be as a predictor of in-depth glucose kinetics, outside of the extremes seen in patients with type 2 diabetes. Over the past three years we have been tracking these metrics closely and found that at least one-third of the time HbA1c is an inaccurate predictor of average blood glucose relative to true average measured by CGM (and this discordance occurs in both directions, meaning sometimes HbA1c overestimates and sometimes it underestimates). In our practice the answer is, how shall I say it, not even close. Is it safe to assume normal fasting glucose (i.e., less than 100 mg/dL) and normal HbA1c (i.e., less than 5.7%) tightly map to low variability and spikes in glucose? The only way to know if they are is to track their blood glucose. Fasting glucose and HbA1c levels don’t necessarily tell us if people are experiencing normal glucose responses. Just because someone’s fasting glucose or HbA1c levels are considered normal doesn’t rule out the possibility that they have high glucose variability, which are large oscillations in blood glucose throughout the day, including episodes of hyperglycemia and hypoglycemia. How do you know if someone has normal glucose responses without tracking their glucose first? Using CGM on someone with “normal” glucose as defined by standard measures such as fasting glucose or HbA1c can determine whether they truly do have tight glucose control and how they respond to different challenges, dietary or otherwise. I want to tell you why I not only disagree with these assertions, but also why this type of thinking may be dangerous to the health of hundreds of millions of Americans.įirst, arguing that there’s little evidence that people with normal glucose responses benefit from tracking their blood glucose is putting the cart before the horse. They also argue that because glucose fluctuations are so small in nondiabetics, a CGM doesn’t provide any meaningful information for them. The author states that “… aside from anecdotal stories, there’s little evidence that people with normal glucose responses benefit from tracking their blood glucose,” according to the perspective. Recently, a perspective in JAMA was published on this topic, highlighting the increasing number of start-up companies promoting the use of CGM in nondiabetics, and included some arguments suggesting that CGMs are “a waste of time and money” for this population. As some of you may already know, I’m a proponent of continuous glucose monitors, or CGMs, in my patients, even if they don’t have diabetes.
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