You may have seen the commercials for FreeStyle Libre devices. Continuous glucose monitors (CGMs) are intended to help improve management of diabetes in patients whose diabetes is not under good control, and also for patients who hate having to keep pricking their finger for blood tests. A small, wearable sensor samples levels of blood glucose in the interstitial fluid (a proxy for blood glucose levels) at frequent intervals. The results can be read on a smart phone. It can alert patients to spikes or drops in the glucose levels, and it can help patients understand how diet, exercise, stress, sleep, and other factors affect blood glucose levels, so they can make appropriate adjustments to their diet and lifestyle.

Now there’s a new kid on the block, Signos. It sells a system with a continuous glucose monitor and support. But it’s not for diabetes. In fact, if you have diabetes you are ineligible. They are selling it for weight loss! And for energy and general health. They advertise: “Discover how your body responds to what you eat, and make small changes to hit your health goals”.

A prescription is required. Signos will help you get a prescription based on your answers to an online questionnaire. The Signos app will provide suggestions and online support.

Annoying and deceptive marketing practices

There is a button on the home page of their website to “request access.” You must answer a series of personal questions and you are warned that there is a long waiting list.

I answered the questions to see what would happen. I was then asked to choose my plan: 6 months for $149 a month, 3 months for $199 a month, or 1 month for @299 a month (marked down from $499 a month). All plans included “AI-powered weight loss insight, digital telehealth assessment, a best-in-class CGM for the duration, and FREE shipping”. The two longer-commitment plans also offered access to an in-app Nutritionist. When I chose the 6-month option, it said the 6-month subscription was $895 without a promo code. If there was a promo code, I didn’t see it. I didn’t subscribe. Shortly after I answered their questions, I received an email from Signos. It said “You’re in, Harriet! We’ve opened up 500 spots this week, so grab yours now. Your spot will be reserved for 72 hours.” A follow-up email arrived the next day, saying “Remember: We hold your spot for 72 hours. Time is ticking.”

The science behind Signos

A tab promises to reveal the latest scientific studies that show the effectiveness of Signos. It lists some studies that speculate about what they hope will be accomplished by Signos, but no studies that look at the actual effectiveness of the system. I thought the information they provided was deceptive, farcical, and insulting. They don’t have any evidence yet! They readily confess “Signos is in the process of conducting research on the feasibility of CGM use for weight loss”.

What that means is that they are hoping to recruit 20,000 customers to be their guinea pigs for a study that is registered in ClinicalTrial.gov and is estimated to be completed by November 1, 2026. The stated purpose of the study is “to collect three years of CGM data to show how efficacious the Signos program is in helping people lose weight, improve body composition, and promote overall wellness”. That’s a misstatement. The data may show “IF” the Signos program helps people lose weight. But without an appropriate control group for comparison, it won’t even show that.

According to ClinicalTrials.gov, “the Signos app will use CGM data to provide recommendations customized to users for promoting general health and wellness”. How can they provide customized recommendations if they don’t even know if the program works?

Conclusion: An untested system

They appear to have great hopes for the Signos program, but marketing Signos now is really jumping the gun. The hopes are not yet supported by any credible evidence, and they have the chutzpah to expect their customers to provide the evidence for them. And to pay for the privilege! I think that’s unconscionable.

Author

  • Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.

Posted by Harriet Hall

Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.