This DiaTribe link has an interesting article on FNIR - Flat, Narrow, Time-in-Range. I think it is getting its data from the ADA article referenced here which @EdD posted.
It mentions:
“What is time-in-range in people without diabetes? A recent study put CGM on people without diabetes for 10 days, finding 97% time-in-tight-range (70- 140 mg/dl), with blood glucose levels averaging 99 mg/dl and showing little variation.”
Just wondering, wouldn’t an average of BG 99 mg/dL indicate the person is pre-diabetic though? And what are their BGs for the remaining 3%?
100 BG as an average does sound too high. (99 - whatever)
I assume outside of mealtimes including overnight the BG is around 80 with the mealtime rises generally to the 140 range as a max are not prolonged so it is hard to see where a 100 BG average comes from.
That was my thought, too! Maybe the uncategorized 3% is even higher than 140?? I was told by an endo that non-D’s do indeed sometimes reach and exceed 140. I was a bit surprised to hear that.
Think Thanksgiving or other “food coma” inducing meals when the body’s insulin storage and production capacity is severely challenged. That’s how it was explained to me.
Here’s another study that assessed glucose profiles of people without D. The sample size was small though. It’s enough to convince me that I don’t need to attempt to flat line after meals. The 24-hour mean in that study is 90.
I think the mean fasting blood sugar (i.e. the 83 mg/DL) that people are always referencing does not apply 2 or 3 hours after a meal – I think you actually have to be fasting for 3 or more hours to hit that. My guess is that most people are in the 60s to 80s overnight, spike to the 120 range after each meal and then settle down to the 90 to 100 range in the 1 to 3 hours after a meal. Go longer than that between meals, and you start drifting into the 80s, 70s and 60s. So I can see 99 mg/DL very easily translating to the average for a normoglycemic person who is eating every 3 hours, as most people in our society do.
Using an A1C calculator, that translates to an A1C of 5.1 which is absolutely bang-on normal.
Seems to be another study from April 2019 using a “Dexcom G6 CGM, with once daily calibration, was worn for up to 10 days”. I can’t access the full publication. Combining useful summary information from 2 sources below
153 participants (age 7-80 years) were included in the analyses. Mean average glucose was 98-99 mg/dL (5.4-5.5 mmol/L) for all age groups except those over 60 years in whom mean average glucose was 104 mg/dL (5.8 mmol/L). The median % time between 70-140 mg/dL (3.9-7.8 mmol/L) was 96% (IQR 93%-98%). Mean within-individual coefficient of variation (CV) was 17±3%. Median time spent with glucose levels >140mg/dL was 2.1% (30 min/day) and <70 mg/dL (3.9 mmol/L) was 1.1% (15 min/day).
Since CGM-based outcomes that are increasingly being used in clinical pediatric diabetes research, this study was aimed at gathering normative sensor data in healthy, non-diabetic children using the recently approved DexCom G6 system. In this multicenter study, healthy, non-diabetic children and adolescents (age 7 to <18 years, BMI between 5th and 85th percentile, and HbA1c <5.7%) were included. Each participant wore a blinded DexCom G6 for approx. 10 days and kept a daily log of exercise, meals, and sleep. Only participants with no positive islet antibodies and ≥72 h of CGM data were analyzed, overall and by age group. Among the 56 healthy non-diabetic participants who were analyzed, 54% were female, 93% non-Hispanic White, mean HbA1c was 5.1% and mean BMI percentile was 51%. Overall mean 24-h sensor glucose level was 99±6 mg/dl. Peak post-prandial glucose was 126 mg/dl. Overall, meal-related increases in sensor glucose resulted in daytime glucose levels 3 mg/dl higher than nighttime values. Sensor glucose levels >120 and <70 mg/dl were not uncommon in either age group but sensor values >180 and <54 mg/dl were rarely observed (Table). As greater emphasis is placed on glycemic metrics beyond HbA1c levels, the current study provides a normative set of sensor glucose levels that can be used for comparison for clinical trials. It is noteworthy that sensor glucose levels >180 and <54 mg/dl were very uncommon in our healthy non-diabetic participants, which support these levels as the thresholds for clinically important hyper- and hypoglycemia in diabetes. With improvements in both pharmacologic agents and mechanical solutions the ultimate goal may be to attain tighter glycemic control in those living with diabetes by altering the hyperglycemic threshold to 160 mg/dl.
Thanks for posting this, @EdD. I find the above Results very surprising, but am relieved to know that healthy individuals can spend some time low/high, too
Re whether non-diabetics go above 140, my ex-gf was at one point worried about diabetes and I started testing her a handful of times. Once after a huge super carby meal, she was like 183 or something. Completely freaked her out. She was totally within normal, non-diabetic range every other reading we did, and her A1c was always perfect. She was still worried about that one errant reading, so at some point I refused to test her any more since she clearly did not have any real blood sugar problems. (I now in retrospect suspect her symptoms she was trying to account for were due to chronic Lyme anyway.) So yeah, I do think on rare occasion, at least some non-diabetics will spike, but they probably come down pretty quickly.
Great data, thanks for posting! I find it rather annoying that these so-called sugar-normal individuals achieve fairly decent results while at the same time being completely oblivious to intricacies of blood glucose control
