Biofeedback: CGM metrics improve after just 4 weeks of dietary intervention

Written by Dr Edward Leatham, Consultant Cardiologist

Today there is  widespread use of continuous glucose monitoring (CGM) in health conscious, non diabetics. In the last few years, there are multiple reports, amplified by social media campaigns supported by Zoe and other lifestyle Apps, that many non diabetics observe spikes in glucose concentrations to high levels normally only seen in diabetics. This observation has certainly stimulated sales in health apps, however could also be of tremendous important in managing common inflammatory diseases such as coronary heart disease (CHD), since even transiently high glucose levels have been shown to lead to damaging free radical release and glycosylation. It is therefore plausible that glucose spikes and high glucose variability (GV) are both important, largely unrecognised risk factor for coronary heart disease, sitting right under our noses! 

Our professional metabolic health assessment (MHA), operated by dieticians and nutritional therapists, incorporates data processing (by MedicalSpace Ltd)  to provide feedback to the patient on their GV status, using both graphical and numerical stats.  We found glucose dysregulation in patients of all ages, both with and without coronary heart disease, however, most exciting of all, by encouraging the use of CGM as a form of biofeedback, by following our professional recommendations provided as part of the MHA , we observed favourable changes in key GV metrics on repeat CGM testing after just 4 weeks.

The example below illustrates improved GV after just four weeks of ‘glucose flattening’ dietary intervention. 

Fig 1 Top panel: episode calculation profile (ECP) in a non diabetic patient with coronary disease which summarises glucose results over 6 days . Normal glucose values (3.9-7.8 mmol/l) are depicted in green, any glucose values over 7.8 mmol/L in red and over 10 mmol/L in dark red. There are multiple glucose spikes present over a week.  In more severe cases, we find multiple spikes each day.  Fig 2: (lower panel). The ‘spikometer ‘, is an overlay of the same glucose data designed to distinguish rapid from gentle glucose changes in body tissue concentrations of glucose. In this example most values are white, indicating more physiological movements of glucose levels. However 5  of these upward spikes in 6 days are very rapid increases (spikes) shown by red dots  and in blue are rapid dips decreases (dips).

The CGM results on the same patient after four weeks of dietary intervention are shown below:

Fig 3&4: after four weeks of a diet ‘hacks’, predominantly reducing or altering timing of occasional  snacks and replacing carbohydrate with fibre meals aimed to slow carbohydrate uptake, the repeat test shows fewer spikes, less time out of the normal range and only two rapid spikes.

By magnifying the viewer you will observe only 1 bright red dot on  the glucose spikogram. 

Table summarising changes over 4 weeks. The last column shows the change in average for each metric pre and post intervention.. It shows a significant shift in some key metrics with healthy ones in green and worsening ones in red:  including  9% improvement in MAGE, a 90% change in ‘high oxidative stress index’, 58% reduction in number of spikes exceeding 10 mmol/L, a 13% reduction in spikes over 7.8 mmol/L and 75% reduction in the number of rapid (glucose rises that exceed 2mg/dL/min) spikes per week.

With such game changing technology becoming widely available in the palm of your hand, and the benefits  of altered lifestyle being demonstrable using affordable  biofeedback systems, we might hope to see plenty of ‘glucose-flattening’ trials underway.

The jury will remain out on the true importance of glucose spikes and increased GV as a novel risk factor, until properly designed clinical trials report positive (one would hope) outcomes, such as reduced risk of metabolic syndrome, diabetes and cardiovascular endpoints. However the wealth of circumstantial evidence already available means that there will be many early adopters; patients; physicians, dietitians and nutritional therapists who will be keen to use CGM technology to steer towards optimising glucose metabolism by promoting lifestyle and dietary interventions, on an intuitive basis. 

Another consequence of CGM as an affordable smartphone app is the interest and commentary being created by younger people. There is a glimmer of hope that wider use of CGM in non diabetics under 30, may lead to a paradigm shift towards healthier food choices and more active lifestyle, without which we will see an ever increasing incidence of cardiovascular diseases presenting from a young age. 

For more information see Metabolic Health Assessment