Is CGM the new CBT?

Lauren is a 45-year-old corporate lawyer who managed to excel in every aspect of her life including parenting her three children while working full time as a corporate lawyer. She had been a math major at Harvard and loved data. Suffice it to say, given that I was treating her for a thyroid condition rather than diabetes, I was a little surprised when she requested that I prescribe her a freestyle libre monitor. She explained that she was struggling to lose 10 pounds, and she thought continuous glucose monitoring (CGM) would help her determine which foods were impeding her weight loss journey.

While I didn’t see much downside to acquiescing, I felt she had probably been spending too much time on Reddit. What information could CGM give a non-diabetic that couldn’t be gleaned from a food label? Nevertheless, Lauren filled the prescription and began her foray into this relatively uncharted world.  When she returned for a follow-up visit several months later, I was shocked to see that Lauren had lost her intended weight. With my tail between my legs, I decided to review the theories and science behind the use of CGM in patients without insulin resistance.

While it’s not rocket science, CGM can help patients through a “carrot and stick” approach to dieting. Lean proteins, non-starchy vegetables, and monounsaturated fats like nuts and avocado all support weight loss and tend to keep blood sugar levels stable. In contrast, foods that are known to cause weight gain (e.g, sugary foods, refined starches, and processed foods) cause sugar spikes in real time. Similarly, large portion sizes are more likely to result in sugar spikes, and pairing proteins with carbohydrates minimizes blood glucose excursions. Though all of this is basic common sense, the constant feedback holds patients accountable for their food choices and helps with behavioral change.

Since blood sugars are influenced  by myriad factors including stress, genetics and metabolism, CGM can also potentially help create personal guidance for food choices.[1]  In addition, CGM can reveal the effect of poor sleep and stress on blood sugar levels, thereby encouraging healthier lifestyle choices. The data collected also may provide information on how different modalities of physical activity affect blood sugar levels. A recent study compared high-intensity interval training (HIIT) and continuous moderate-intensity exercise on post-meal blood sugars in overweight individuals without diabetes. CGM revealed that HIIT is more advantageous for preventing post meal spikes. [2]

While CGM appears to be a sophisticated form of cognitive behavior therapy, I do worry that the incessant stream of information can lead to worsening anxiety, obsessive compulsive behaviors or restrictive eating tendencies. Still, thanks to Lauren, I now believe that real-time CGM may lead to behavior modification in food selection and physical activity. 

[1]  Berry S, Valdes A, Davies R, Delahanty L, Drew D, Chan AT, Segata N, Franks P, Spector T. Predicting personal metabolic responses to food using multi-omics machine learning in over 1000 twins and singletons from the UK and US: the PREDICT I study (OR31-01-19) Curr Dev Nutr. 2019;3:3130642.

[2]  Little JP, Jung ME, Wright AE, Wright W, Manders RJ. Effects of high-intensity interval exercise versus continuous moderate-intensity exercise on postprandial glycemic control assessed by continuous glucose monitoring in obese adults. Appl Physiol Nutr Metab. 2014;39:835–41.