For 28 days, I had a tiny needle stuck in the back of my arm, reading my blood. I’m neither diabetic nor pre-diabetic, but I jumped at the opportunity to wear a continuous glucose monitor (CGM) as part of the Wearable Challenge.
As a child, I’d suffered from spells of hypoglycemia (blood sugar dropping below 70 mg/dL). I would experience cold sweats, lightheadedness, trembling hands, and an elevated heart rate from my body releasing epinephrine (adrenaline) to stabilize my blood glucose. Dealing with low blood sugar led me on a years-long journey of self-experimentation, in which I would try new foods and habits with the hopes of improving my health. My curiosity for seeking ways to optimize my diet eventually led me to enroll in the challenge.
How It Worked
Participants of the 28-day challenge paid $850 upfront ($150 to cover the continuous glucose monitor and access to the app, and $700 as a wager). Every day you stayed below the 120mg/dL challenge limit, you would be repaid $25. If you were perfect for the full 28 days, you only paid the cost of the continuous glucose monitor. Talk about having real skin in the game.
(For context, the International Diabetes Federation (IDF) guidelines state that your glucose values are “normal” if they stay below 140mg/dL after meals and return to pre-meal levels within two to three hours.)
The challenge started with participants applying their continuous glucose monitor to the back of their arm. While the idea of sticking myself was a bit scary at first, the CGM’s easy-to-use applicator made the process quick and painless. Once applied, I almost forgot I was wearing it except for when I had to scan the sensor to get my latest glucose reading.
What I Learned
Overall, the challenge was a fun experiment filled with moments of self-confirmation, utter disappointment, and a few surprises in between. I even managed to lose about eight pounds, despite weight loss not being my primary objective.
Here’s a summary of the highs and lows.
The best news was discovering that my go-to breakfast of eggs, bacon, and half an avocado drizzled with olive oil and an afternoon snack of raw almonds had almost no effect on my blood sugar after eating. Since I routinely eat these foods, it was nice knowing that I had already built a solid nutritional foundation.
The challenge also supported my belief that eating a low-carb diet consisting of mostly meat, vegetables, and healthy fats (olive oil, coconut oil, and butter/ghee) is optimal for maintaining consistent glucose levels. I’ve made a conscious effort to avoid simple carbs, vegetable oils, and sweeteners when cooking, and this challenge confirmed that I should continue to keep these out of my diet as much as possible.
The least surprising foods that had the most significant impact on my blood sugar were white rice and beer. Unfortunately, I love both things. Even consuming the white rice on a few sushi rolls was enough to spike my glucose levels well above the 120mg/dL threshold.
I was also disappointed to learn how much sweet potato spikes my blood sugar. I knew sweet potatoes had a lower glycemic index (GI) score than regular potatoes, but they still pushed me well over the limit when roasted or cooked in a stew. Going forward, I still plan to keep them in my diet, but will be more mindful about how often I eat them.
The biggest disappointment was discovering how much a cheat meal wrecked my glucose levels. And it wasn’t just the initial glucose spike that was bad, but how long my glucose levels stayed elevated.
For example, one weekend, I decided to take a risk and enjoy some Indian food for dinner. The butter chicken and garlic naan were delicious, but they not only shot my glucose levels past 150mg/dL but also kept my glucose levels elevated well into the next day! Losing $50 from one cheat meal made me reconsider how much they’re really worth.
Perhaps the biggest surprise was discovering that quality tequila had almost no effect on my blood sugar, unlike beer, which would spike my glucose levels as high as 160mg/dL. The difference is that 100 percent agave tequila has zero carbs, whereas an average beer has around 13g. Since beer is my usual go-to if I want a drink, I was happy to learn there was a healthier substitute I already enjoyed.
I also recognize I need to be careful here: Just because I didn’t experience a glucose spike after a drink doesn’t mean I didn’t have a biological response. A study in The American Journal of Clinical Nutrition suggests that alcohol decreases the liver’s ability to make new glucose, which can trigger hypoglycemia—especially if you’re fasting or in a ketogenic state.
The other unexpected takeaway for me was discovering that my glucose levels aren’t just impacted by what I eat but also by what time I eat. I had no trouble confirming this because I prefer meal prepping and will routinely eat the same meal two or three days in a row to save time.
Eating the same meal for lunch and dinner for multiple days in a row was great for understanding how my body responds to food at different times of the day. All else being equal, my glucose spiked more after dinner than it did after lunch, and sometimes as much as 20mg/dL. Perhaps there’s a reason why, but I couldn’t find a convincing explanation.
What I’ve Changed
Since the challenge ended, I’ve made a few adjustments to my diet and lifestyle. I’m not one to make radical changes (like cutting out a particular food from my diet forever), but I’m more careful about when and how often I want to indulge.
Some changes I’ve made include:
- Now that I’m aware that the effects of an unhealthy meal can last for up to two or three days, I’m more selective about when and what I choose for a cheat meal.
- I try to avoid any sweetened beverages, no matter how “healthy” they’re advertised. Though frequently praised as healthy choices, smoothies, sweetened kombucha, and sweetened coffee wrecked my glucose levels.
- I’m more conscious of what I order when I eat out. For example, I opt for the salad at Chipotle instead of the burrito bowl to avoid the rice. I’ve also switched to eating more sashimi than sushi, which has less rice.
- I try to go on brief walks after big meals since it seems to help mitigate any post-meal glucose spikes.
- If I decide to drink, I try to opt for quality spirits (neat or on the rocks) over craft beer or cocktails loaded with sugar.
Even though the challenge only lasted a month, I learned more about my diet and lifestyle in those four weeks than I had from any previous blood test or book on dieting. And while I don’t want to conflate stable glucose levels with perfect health, tracking your glucose with a CGM gives you the agency to observe, decide, and act towards making healthier choices.