Should Healthy Individuals be Monitoring their Blood Glucose?
Posted:
2024-09-03
What’s happening?
Recently, there has been increased marketing for continuous glucose monitoring (CGM) directed towards non-diabetic populations (1-3). Continuous glucose monitors (CGMs) are currently authorized for sale in Australia, Canada, UK and the US. There are restrictions in making claims for their use for people without diabetes, however this does not restrict public access and some devices that require a prescription can be purchased over-the-counter or online.
Individuals who do not have diabetes may choose to use CGMs under the impression that they can improve their overall health and wellness. This includes monitoring glucose patterns to avoid diabetes, motivating behaviour change to adopt ‘healthier’ choices, and enhancing mental and physical performance, including optimizing peak physical performance for elite athletes (1,4,5).
While continuous monitoring of body metrics is aligned with ongoing trends to personalize nutrition and wellness (e.g., daily step count), critics suggest that additional health information is not necessarily required to help inform or support healthy nutritional choices (2,4). In addition, specific apps that utilize CGM to help personalize nutrition advice may not be that usefulful given the limited data that is collected (3).
The PEN® Team looked for available research about the use of CGMs and whether supporting their use in the general population is beneficial.
Analysis
Unlike HbA1C that provides an index of glycemic exposure over 2-3 months, CGM provides detailed information on short-term glucose variability, including hypoglycemia (6). CGM can add information to HbA1C; however because CGM technology measures subcutaneous interstitial glucose (rather than plasma, serum or capillary), results may be affected by blood flow and other factors. CGM sensors are influenced by placement and calibration of the device, and different sensors can provide different results.
A narrative review of the literature identified eight studies of CGMs used in people without diabetes, which reported that blood glucose levels stayed within the normal range (3.9 to 7.8 mmol/L) most of the time (>90% of time in this range over 3 to 14 days of wear) (5). This draws into question the value of using CGMs outside of metabolic diseases like diabetes. Only a few studies have explored using CGMs in healthy individuals to monitor glycemia in response to diet and exercise (5,7):
Postprandial hyperglycemia (>7.8 mmol/L) is expected one to two hours after eating in individuals without diabetes (7). Using CGMs, glucose responses have been shown to vary widely among otherwise healthy individuals given the same foods / meals (5,7). This has led researchers to suggest that individuals could be grouped according to patterns of glycemic responses called glucotypes (e.g. low, moderate and severe glucotype based on increasing variability in response). Glucotype classification of healthy individuals along with analysis of other individual factors (e.g. anthropometrics, biomarkers, gut microbiome) may be a useful method in the future to identify early metabolic dysfunction.
Exercise effects on glycemic profile using CGMs in healthy individuals has not been well studied (5). One study observed a small reduction in mean glucose concentration following exercise (~15% reduction from baseline to nadir); however, in another small study of sub-elite athletes, high blood glucose was reported to be a greater issue than low blood glucose (5). No studies in healthy individuals or elite athletes have examined whether CGMs can be used to attain a narrow range of blood glucose and whether this impacts exercise performance
Given the limited studies and the high cost of CGMs (~ C$3500/year (2)), currenlty there does not appear to be a reason to recommend their use in individuals without diabetes. If people choose to pay for their equipment, some observational studies support the idea that feedback from CGMs can be a motivational tool to improve diet and physical activity behaviours (5,7). More research is needed to develop standards for how to respond to abnormal CGM values and whether improved glycemic variability improves health outcomes, including decreased risk of diabetes, mental health improvement and improved sleep patterns.
What now?
Dietitians may be getting questions from their clients wanting to know the potential benefits and risks of CGM. Additional research is needed to answer the following questions if clients are using CGMs to help the dietitian / health care provider support their nutritional goals (5):
Does CGM improve diet and does improved diet lead to less diabetes?
Does CGM improve sleep?
What kind of improvement in blood glucose is needed to achieve the improved outcomes in questions i - ii? What is the most important glycemic target to address: improved fasting, postprandial, or mean blood glucose or is it time in range or glycemic risk index?
What is the role of improved glycemic variability on outcomes in individuals without diabetes and in athletes?
There are some risks associated with using CGMs including cost as mentioned, skin irritation (5) and distress that may occur around food / eating with an individual having access to continuous data (2). Consideration should also be given to the lack of consensus guidelines for defining and treating abnormal blood glucose values using CGMs in people without diabetes (5). This information should be shared with clients so they can make an informed decision around the use of a CGM.
Additional research tracking use of CGMs by non-diabetic populations can help clinicians become more aware of glycemic patterns or glycemic responses and even identify new genetic and genomic biomarkers in the future that may predict increased risk of diabetes (5). Until then, dietitians can provide current practice advice to adopt a healthy eating plan and include daily movement and activities to help to reduce diabetes risk (8).
As with other data-driven health information, clients will need to check when they obtain devices if there is also access to health care support to interpret and apply the information to improve their health.
See Additional Information:
PEN System content and resources:
3rd party client resources on preventing diabetes:
References:
Bowler A, Cox G. Non-diabetics are buying continuous glucose monitors - but are they actually any health benefits? The Conversation.com July 22, 2024. Available from: https://theconversation.com/non-diabetics-are-buying-continuous-glucose-monitors-but-are-there-actually-any-health-benefits-232171
Zafar A, Birak C. Wearable technology trends now include healthy people tracking their blood glucose. Is it worth it? CBC News. December 29, 2023. Available from: https://www.cbc.ca/news/health/wearables-continuous-glucose-monitors-1.7068390
Baggini J. Personalizing stuff that doesn’t matter’: the trouble with the zoe nutrition app. The Guardian. May 2024. Available from: https://www.theguardian.com/science/article/2024/may/18/zoe-nutrition-app-diet-tim-spector-wellness-science
Shmerling, R. Is blood sugar monitoring without diabetes worthwhile? Harvard Health Publishing. April 24, 2024. Available from: https://www.health.harvard.edu/blog/is-blood-sugar-monitoring-without-diabetes-worthwhile-202106112473
Klonoff DC, Nguyen KT, Xu NY, Gutierrez A, Espinoza JC, Vidmar AP. Use of Continuous Glucose Monitors by People Without Diabetes: An Idea Whose Time Has Come? J Diabetes Sci Technol. 2023 Nov;17(6):1686-1697. doi: 10.1177/19322968221110830. Epub 2022 Jul 20. PMID: 35856435; PMCID: PMC10658694. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/35856435/
Selvin E. Hemoglobin A1c-Using Epidemiology to Guide Medical Practice: Kelly West Award Lecture 2020. Diabetes Care. 2021 Sep 21;44(10):2197–204. doi: 10.2337/dci21-0035. Epub ahead of print. PMID: 34548283; PMCID: PMC8929182. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/34548283/
Jarvis PRE, Cardin JL, Nisevich-Bede PM, McCarter JP. Continuous glucose monitoring in a healthy population: understanding the post-prandial glycemic response in individuals without diabetes mellitus. Metabolism. 2023 Sep;146:155640. doi: 10.1016/j.metabol.2023.155640. Epub 2023 Jun 24. PMID: 37356796. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/37356796/
Galaviz KI, Narayan KMV, Lobelo F, Weber MB. Lifestyle and the Prevention of Type 2 Diabetes: A Status Report. Am J Lifestyle Med. 2015 Nov 24;12(1):4-20. doi: 10.1177/1559827615619159. PMID: 30202378; PMCID: PMC6125024. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/30202378/