The Glucose and Blood Sugar Issue: Q&A with Dr. William Li

Rob Corso

October 3, 2025

Glucose is the quiet conductor of your biology. It dictates how your brain thinks, how your muscles perform, how your hormones signal, and how your body ages. Every system depends on keeping it in rhythm.

Last Saturday, we went deep into glucose: what drives spikes, how your body responds, and why managing it well is one of the most powerful levers for health and longevity.

Missed it? You can still catch up on The Glucose and Blood Sugar issue

Dr. William Li is the author of the New York Times bestsellers Eat to Beat Disease: The New Science of How Your Body Can Heal Itself and Eat to Beat Your Diet: Burn Fat, Heal Your Metabolism, and Live Longer. His groundbreaking research has led to the development of more than 40 new medical treatments that impact care for more than 70 diseases, including diabetes, blindness, heart disease and obesity.

His TED Talk, “Can We Eat to Starve Cancer?” has garnered more than 11 million views. Dr. Li is the president and medical director of the Angiogenesis Foundation, and he is leading global initiatives on food as medicine. The latest cutting-edge information on food as medicine, metabolism, and longevity can be found on Dr. Li’s YouTube Channel.

Q. Is it necessary to eat a clean, sugar-free diet in order to keep blood glucose stable—especially for someone with prediabetic range lab results?

Not necessarily. The keys to metabolic stability for healthy aging, including blood glucose behavior, are your dietary pattern, quality and quantity of food consumed, timing of eating, and integration of diet with regular exercise, getting good quality sleep, and stress management.

Someone with pre-diabetes can restore their metabolic balance with plant-based foods, lean proteins, and healthy fats, while minimizing refined starches, added sugars, and ultra processed foods. It’s never too late to turn the ship around, especially with pre-diabetes.

Importantly, one size does not fit all. Individual physiology matters, so a personalized nutrition and lifestyle intervention is the best approach for success.

Q. How would you support someone who loves desserts, snacking, croissants, and bread, etc. to make a permanent lifestyle shift to curb and reverse mitochondrial dysfunction and prevent them from developing more chronic disease?

We know from human studies that the pattern of eating a high carb diet with lots of added sugar is the road to metabolic syndrome and Type 2 diabetes, leading to the downstream pathologies associated with chronic disease. Metabolic syndrome and Type 2 diabetes are conditions associated with mitochondrial dysfunction, impaired ATP production, and lower mitochondrial density, hence the shift in energy and fatigue people experience.

To counter this, a lifestyle shift that involves caloric restriction, low glycemic foods, and minimal carbohydrates can be a powerful lever to revert metabolism and mitochondrial dysfunction back toward a healthy set point.

Q. Besides obvious sugar/processed carbs, what other foods impact blood glucose, perhaps something that is common but most people might be unaware of??

There are some foods that are often considered “healthier” that are surprising triggers for a rapid rise in blood glucose. Some examples are sweet potatoes, beets, flavored yogurt, granola bars, and dried fruits.

Q. How much does sleep quality and duration actually affect blood glucose regulation? Can improving sleep alone significantly improve glucose control?

A good night’s sleep helps to optimize insulin sensitivity and maintain healthy blood glucose levels. Poor sleep does just the opposite, dropping insulin sensitivity by as much as 30%. Some common forms of poor quality sleep include fragmented sleep, sleep deprivation, and sleep apnea. These can also increase cortisol secretion, which also elevates blood glucose.

Sleep is therefore an important regulator of glucose metabolism, though it doesn’t act alone. A low glycemic diet consisting of high-quality calories, coupled with portion control, exercise, and stress management are other key partners for maintaining a healthy metabolism.

Q. Are natural sweeteners like honey, maple syrup, or agave any better for blood sugar than refined sugar, or are they essentially the same from a metabolic standpoint??

All of these natural sweeteners contain different forms of sugar. From a clinical perspective, they have very similar overall effects on metabolism. Small differences do exist between these sweeteners in the ratio of different forms of sugar (glucose vs. fructose vs. sucrose), and they are processed slightly differently in the body.

But when it comes to net effect, they are comparable. The key for health when it comes to sugar is to be very sparing in its consumption, in any form.

The views expressed by our expert are entirely their own. There is no financial, professional, or organizational affiliation between the expert featured in this Q&A and our sponsor.

Disclaimer: This newsletter is provided for educational and informational purposes only and does not constitute providing medical advice or professional services. The information provided should not be used for diagnosing or treating a health problem or disease, and those seeking personal medical advice should consult with a licensed physician.