The Diabetes Code Summary

In The Diabetes Code, nephrologist Jason Fung argues that type 2 diabetes is fundamentally a disease of excess dietary sugar and refined carbohydrates, not an inexorable progressive condition. He builds on the framework introduced in his earlier book The Obesity Code, applying it specifically to diabetes: chronic hyperinsulinemia, driven by frequent eating and high-carbohydrate intake, leads to insulin resistance and fat accumulation in the liver and pancreas. Fung distinguishes between the two main drivers of high blood glucose—dietary glucose and the liver's own production of glucose—and contends that standard treatments focused only on lowering blood sugar with medication fail to address the underlying cause. A central argument is that type 2 diabetes should be understood as a reversible condition of fat storage rather than an inevitably worsening disease. Fung critiques conventional dietary advice, particularly low-fat, high-carbohydrate recommendations, and questions the reliance on insulin and other glucose-lowering drugs, which he says can worsen weight gain and insulin resistance. He explains concepts such as the difference between type 1 and type 2 diabetes, the role of the pancreas in producing insulin, and how excess insulin promotes further fat storage. Fung's proposed solution centers on dietary changes that reduce insulin levels, including low-carbohydrate and ketogenic diets, and intermittent fasting. He presents clinical observations and published case reports suggesting some patients have reduced or eliminated diabetes medications under medical supervision. He emphasizes that any such changes require physician guidance, especially for those on insulin. The book also covers complications of diabetes, the history of its treatment, and why Fung believes current management often treats symptoms rather than causes.