Continuous Glucose Monitors: A Revolution in Diabetes Management and Beyond

Continuous glucose monitors (CGMs) that do not require regular finger prick calibration only became available in 2016 [1].  These were primarily aimed at aiding insulin-dependent diabetics in managing hypoglycemic attacks which are serious conditions that lead to numerous hospitalizations and deaths worldwide each year.  By providing real-time measurements of tissue glucose levels, CGMs  give individuals more precise information about their blood sugar trends, potentially averting severe outcomes like comas and improving glycaemic control and ‘time in range’. Early trials have indeed confirmed the efficacy of these devices in helping manage diabetes more effectively.

Emerging Applications Beyond Diabetes

By 2018, intriguing findings began to emerge about the application of CGMs in non-diabetic individuals. Reports and trial results showed that people without diabetes also experience significant glucose spikes, typically only observed in diabetic patients. This revelation highlighted that many individuals, who do not meet the criteria for pre-diabetes or Type 2 diabetes, display significant blood sugar fluctuations following certain meals or foods, and while high blood glucose values, just like high blood pressure, generally do not create symptoms at the time, low blood sugars appear to be associated with symptoms that may drive unhealthy snacking.

These observations led to the concept of “glucose dysregulation” and “high glucose variability,” which are now considered potential factors in long-term conditions such as chronic inflammatory diseases, including coronary heart disease, dementia, and arthritis. The implication is that glucose management might play a role in the broader spectrum of health issues, beyond the traditional boundaries of diabetes.

The Rise of CGMs Among the Health-Conscious

The use of CGMs has seen a dramatic increase among non-diabetics keen on improving their health, driven in part by popular lifestyle apps like Zoe. These platforms have contributed to a booming market, promoting the idea that anyone might benefit from understanding more about their body’s glucose responses. Consequently, CGMs are now more accessible, available in places like supermarkets, and pushed by various vendors eager to capitalize on this growing health trend.

Medical Professional’s Caution

However, the medical community remains cautious about embracing this technology wholesale for non-diabetic use. History shows that even seemingly beneficial treatments can have unexpected downsides when subjected to rigorous testing. For example, the ACCORD study published in the New England Journal of Medicine in 2008, which investigated whether tight glucose control improved health outcomes, had to be terminated early due to an excess of deaths in the aggressive treatment group[2,3]. It is also well known that although high HbA1c codes for higher cardiovascular deaths, low HbA1c is a risk factor for increased all cause mortality [4].

As such, many professionals advocate for more comprehensive trials to determine whether non-diabetic glucose fluctuations are a significant cause of medical conditions and whether interventions to modify these spikes can effectively improve health outcomes.

Understanding Glucose’s Role in Non-Diabetic Conditions

Research has well-documented how poor glucose control in diabetics can exacerbate conditions like heart disease by accelerating atherosclerosis. Studies have also shown that diabetic patients with frequent and higher glucose spikes tend to have worse outcomes following acute coronary events, such as higher rates of restenosis in stented arteries. Simple measures of glucose variability have been shown in large population studies to link to future cardiovascular events, and although yet to be formally tested, there is evolving evidence that high glucose variability may well be an important risk factor for cardiovascular disease.

The challenge arises with non-diabetic individuals, where no direct data yet links glucose dysregulation with poor health outcomes—simply because the necessary studies haven’t been conducted. It’s plausible that glucose management could be a missing link in understanding heart disease, given that traditional risk factors do not fully explain all cases of coronary heart disease.

A Pragmatic Approach to Glucose Management

In the absence of strong evidence from randomised controlled trials, a pragmatic approach involves educating patients about the current knowledge gaps while encouraging lifestyle changes that are generally beneficial. These include reducing carbohydrate intake, choosing lower glycemic index foods, increasing physical activity, and improving sleep quality. Such measures are unlikely to be harmful and could potentially lead to improved overall health and well-being.

By analyzing the CGM data of a healthy patient (Fig 1) alongside that of a patient experiencing disease progression despite low LDL levels (Fig 2), the visual comparison makes it clearer than words alone could. It seems logical for a physician to advise the patient in Fig 2 to attempt to reduce their glucose response to meals to below 7.8 mmol/L. There are numerous strategies available online for lowering glucose levels, including many collected together within my Instagram collection titled ‘Breakfast’. Early experience seems to show that by altering one’s diet and in particular increasing fibre intake at breakfast and reducing carbohydrate, possibly due to changes in the gut microbiome, we can certainly see encouraging changes/ ‘improved’ glucose regulation within a few months.

Fig 1

Fig 2

CGMS are not as accurate as carefully calibrated lab glucose assays, particularly at glucose concentrations <3 mmol/L, however they appear to display reasonably accurate ‘real time’ responses to food intake. By studying patterns in our different patient populations it also appears to be possible to distinguish healthy from unhealthy glucose regulation in our non diabetic patients.  We standardise the X and Y axis on episode metrics graphs to facilitate comparison and, based on literature review and international standards for diabetes, set our reference ranges of healthy as 3.9-7.8 mmol L (70-140 mg/dL), mildly elevated and mildly unhealthy being >7.8 mmol/L (140 mg/dL) and unhealthy as >10 mmol/L (180 mg/dL).  By feeding this information back to patients with any forms of coronary artery disease, along with education and goals, we believe it helps to empower patients to bring about lifestyle and dietary changes that will one day be proven to reduce inflammation linked to coronary artery disease. Early reports indicate that many patients who embrace this technology report improved wellness scores and significant weight reduction.

More controversial is the idea of treating at-risk patients with new drugs outside of well-conducted trials. Until there is sufficient evidence to support such treatments, the focus should remain on dietary and lifestyle modifications.

Conclusion

Ultimately, for patients with heart disease and observed glucose dysregulation, simple dietary changes to manage blood sugar levels can be a positive step. Not only can these adjustments lead to better metabolic health, but they also promote weight loss and overall well-being—a clear benefit from using CGMs as part of a broader health assessment strategy. The journey of CGMs from a niche medical device for diabetics to a potential tool for widespread health improvement illustrates the evolving understanding of glucose in human health.

1.  Introduction: History of Glucose Monitoring
2. ACCORD Trial Effects of Intensive Glucose Lowering in Type 2 Diabetes 2008
3. NPC Archive Item: Increased death rate found in intensive blood glucose-lowering arm of trial in type 2 diabetes – study arm halted

4. Low Hemoglobin A1c and Risk of All-Cause Mortality Among US Adults Without Diabetes