Researchers have proposed that a simple finger-prick blood test could become a practical tool for monitoring metabolic health in people with cancer and other chronic diseases. The approach, described in the journal Frontiers in Science, focuses on the glucose ketone index (GKI)—the ratio of blood glucose to ketone levels—which may provide insight into the body's metabolic state and the effectiveness of lifestyle interventions.

Noncommunicable diseases (NCDs), including cancer, cardiovascular disease, type 2 diabetes, obesity and neurodegenerative disorders, currently account for the majority of deaths worldwide and are expected to become an even greater global health burden by 2050.

The researchers suggest that the GKI could help determine whether dietary changes, fasting or physical activity successfully shift the body into nutritional ketosis—a metabolic state characterized by lower glucose levels and increased ketone production. This shift has been associated with improved mitochondrial function and may contribute to better management of certain chronic diseases. However, the authors emphasize that disease-specific target GKI ranges still need to be established through large clinical studies.

The glucose ketone index was originally developed to monitor adherence to ketogenic dietary therapies in cancer treatment. It measures the relationship between blood glucose and β-hydroxybutyrate, the primary ketone body produced during ketosis. According to the researchers, assessing both markers provides a more comprehensive picture of metabolic health than measuring glucose or body weight alone.

Lower GKI values indicate lower blood glucose and higher ketone availability, reflecting metabolic conditions associated with more efficient mitochondrial energy production. Higher GKI values may indicate impaired metabolic function, characterized by elevated glucose and reduced ketone levels.

Scientists believe that routine GKI monitoring could help physicians evaluate whether interventions such as dietary modifications, fasting or exercise reduce chronic inflammation, high blood sugar, elevated insulin levels and oxidative stress—all of which are linked to the development and progression of many chronic diseases.

The authors stress that ketogenic strategies should be viewed as supportive management tools rather than cures and should always be implemented under medical supervision.

They also call for standardized clinical studies to determine optimal GKI target ranges for different diseases and to investigate how GKI measurements relate to disease progression, treatment response and long-term health outcomes. In addition, future research should evaluate GKI alongside other metabolic markers, including insulin, triglycerides and inflammatory biomarkers, to better understand its clinical value.