American Nutrition Association backs finger-prick GKI test to track metabolic health

The American Nutrition Association (ANA) calls for the wider use of evidence-based biomarkers in personalized nutrition care to manage chronic diseases. It highlights the potential of a new real-time biomarker test for metabolic health based on a blood sample drawn from a finger prick. However, the organization tells us policy changes and medical nutrition training are key to ensure equitable access to these tests. 

Detailed in a paper in Frontiers in Science, the new biomarker test called the glucose ketone index (GKI) could potentially help track and manage the metabolic dysfunction behind cancer, cardiovascular disease, type 2 diabetes, obesity, and neurodegeneration.

The research notes that the ratio of glucose to ketones can be linked to the risk of chronic diseases and may help predict risk more accurately than a glucose reading alone. The authors say low GKI ratios are hypothesized to decrease risk, linking a high GKI to increased risk.

The scientists who developed the test suggest that, in the future, the readout may help assess metabolic state, track patient adherence to long-term nutritional protocols, and monitor dietary approaches to improving mitochondrial function, which is linked to many non-communicable diseases.

Nutrition Insight speaks to Corinne Bush, ANA CEO, who recently co-authored a paper advocating for the test’s more widespread utility. She warns that personalized nutrition and metabolic science are moving “faster than the system built to deliver it.”

ANA stresses that US medical schools still don’t require a clinical nutrition course and that fewer than 15% of practicing health care providers say they are comfortable discussing nutrition with patients.

“Patients that could benefit most from GKI-guided care are those that are highly motivated to follow a personalized ketogenic diet and have conditions such as type 2 diabetes where ketosis has been shown to play a major role in treatment and even reversal,” says Bush.

“Without this tool, treatment may involve months of trial and error before a patient and their provider can tell whether a nutrition intervention is working. A tool that shortens that feedback loop should enhance patient compliance, increasing its value.”

She adds that the best candidates for this test are not only people with a particular diagnosis. “They are motivated patients for whom nutritional ketosis is an appropriate therapeutic strategy, who can monitor safely, and whose progress is assessed through GKI alongside symptoms, medications, and established biomarkers.”

Redefining convenience in therapeutic nutrition

Metabolic tracking and tailored medical nutrition are increasingly seen as complementary and essential tools to accompany conventional healthcare protocols. In clinical settings, the GKI could help certified nutrition specialists design and refine therapeutic nutrition programs for more holistic chronic disease prevention and management.

Originally, the GKI was developed as a blood biomarker for tracking cancer patients’ adherence to their prescribed therapeutic diets. It measures the ratio of blood glucose to β-hydroxybutyrate — a ketone body that the study authors link to more efficient mitochondrial ATP production, which is how cells generate usable energy.

Metabolic tracking and tailored medical nutrition are increasingly seen as complementary and essential tools to accompany conventional healthcare protocols.Rather than making patients wait months to receive conventional laboratory results, the test allows practitioners to observe a patient’s metabolic response to changes in carbohydrate intake, meal timing, physical activity, and other interventions, and to adjust the personalized nutrition plan based on near-real-time data.

“The GKI could give personalized nutrition professionals a simple, low-cost, real-time window into an individual’s metabolic state,” Bush explains. “By calculating the ratio of blood glucose to blood ketones, the GKI indicates the extent to which the body is relying on glucose versus ketones for fuel.”

“A lower GKI generally reflects a metabolic profile associated with better mitochondrial function, which research increasingly links to lower risk across a range of chronic conditions, including cancer, cardiovascular disease, type 2 diabetes, obesity, and neurodegeneration.”

The paper suggests that nutritional ketosis, evaluated through the GKI, could be broadly used to reduce chronic high blood glucose and insulin while also raising the body’s production of β-hydroxybutyrate — a shift that could enhance mitochondrial energy production, support metabolic balance, and potentially reduce disease risk or progression.

The authors call for studies to standardize reporting of glucose, ketone, and GKI values, ideally weekly or daily, whenever ketosis is assessed clinically. They say previous studies often report ketone or GKI values too infrequently, which has made comparison difficult.

They also recommend that future studies should report other blood biomarkers alongside the GKI — including triglycerides, inflammatory markers, and insulin — to clarify whether a low GKI correlates with broader metabolic changes. 

Gap in policy, not knowledge

Bush notes that certified nutrition specialists have been using biomarkers to guide and adjust individualized nutrition and care for decades. “What’s new with a tool like the GKI is how simple, affordable, and accessible it can be, which is exactly why it’s gaining attention now.”

The ANA singles out reimbursement reform as the most immediate approach to making this test more widely available. It argues that covering guideline-led biomarker testing without added administrative friction is a change insurers could make now.

Additionally, the organization calls for sweeping legislative and insurance reform so trained nutrition specialists can effectively guide patients through this data.

“This is exactly the question our Policy Outlook was written to answer,” says Bush. “The ability to interpret a biomarker like the GKI and translate it into a personalized nutrition strategy requires rigorous training in clinical personalized nutrition science, which is precisely what the certified nutrition specialist practitioner is trained to do.”

“Here’s why we are calling for change — nutrition education is not part of the training of most physicians and allied health professionals. In general, US medical schools don’t require a single clinical nutrition course, and fewer than 15% of practicing health care providers say they’re comfortable discussing nutrition with patients,” she underscores.

“The professionals trained in personalized nutrition already exist. They’re just not consistently licensed to practice at the level of their training, and personalized nutrition services are often not reimbursed by insurance companies. That’s a policy gap, not a knowledge gap.”

Improving consumer access and usability

Overall, the scientists say GKI works best as a tool for monitoring whether a ketogenic intervention is producing its intended metabolic effect. Bush notes that research has not yet validated a universally desirable GKI or disease-specific targets for the general population.

“Its broader promise lies in helping practitioners identify the degree of carbohydrate restriction or ketosis — if any — that produces the best overall clinical outcomes for each individual.”

Bush anticipates more consumer platforms built around real-time biomarkers like the GKI, which may benefit patients actively paying closer attention to their metabolic health. “My hope is that as these platforms grow, they build in genuine access to certified nutrition specialists rather than attempting to replace expertise with an algorithm. That’s the direction that actually serves consumers.”

“Without a qualified personalized nutrition professional to contextualize a given biomarker value as part of a comprehensive assessment, a number on an app doesn’t translate to positive outcomes and may lead to adverse outcomes.”