People often do lab testing to get a better idea of what’s going on with their health. But finding the answers doesn’t need to involve countless lab tests — but rather the right tests.
A select group of biomarkers can reveal patterns in biology that routine panels often miss, including early shifts in stress levels, energy regulation, inflammation, and detoxification abilities.
Despite this, preventative health screenings remain widely overlooked. Research shows that only 8 percent of people get regular preventive screenings; 18 percent skip doctor visits and tests altogether due to fear of the results.
These numbers reflect a deeper issue: Despite wanting better health, many people avoid the data that can empower them to achieve it.
In the context of longevity, biomarkers can home in on biological aging, metabolic stability, cellular function, and the resilience of key organ systems. They can reveal early shifts in your health well before symptoms appear. With this information, you can identify subtle imbalances, understand your biological age, and take targeted steps to support metabolic, hormonal, immune, and mitochondrial function.
The following five biomarkers can show where your physiology is strong and where issues may be emerging or existing. Understanding them can help you and your healthcare team create a roadmap for better energy, stronger performance, and a healthier, longer life.
1. Cortisol
What test to ask for: Fasted morning serum cortisol that’s drawn between 7 and 9 a.m.
Optimal ranges: 12 to 17 mcg/dL
Cortisol is the body’s primary stress hormone and one of the most significant biomarkers for understanding how well your system adapts to daily demands. It affects metabolism, inflammation, energy production, immune function, blood pressure, and cognitive performance.
In a healthy state, cortisol follows a natural rhythm that supports stable energy during the day and restorative sleep at night. Cortisol is meant to rise in the morning to help you wake up, stay alert, and fuel activity. As the day goes on, it should gradually decline so melatonin can take the lead in the evening, guiding you into deep, high-quality sleep.
Our modern day-to-day routines often push cortisol outside this pattern. Constant stress from demanding schedules, long hours, intense training, or ongoing pressures can flatten or shift this daily rhythm. Instead of possessing a responsive system, your body can slip into chronic survival mode.
This does more than disrupt mood or energy. Elevated or dysregulated cortisol can affect a variety of health factors:
- Insulin sensitivity
- Thyroid function
- Immune resilience
- Gut health
- Sex hormones
- Inflammatory signaling
- Metabolism
- Resilience and recovery
Over time, these disruptions contribute to allostatic load, or the internal wear and tear that can accelerate biological aging.
The impact of stress is measurable. Shifts in cortisol patterns can be symptomatically detected through your energy levels, sleep quality, cognitive focus, and even how your body stores fat. Imbalanced cortisol is often at the root of many common symptoms people dismiss as “normal life.”
Cortisol is a central regulator of the Metabolic Code’s Adrenal-Thyroid-Pancreas Triad, which influences how your body produces and uses energy throughout the day. When cortisol is balanced, this system works smoothly; when it’s dysregulated, the entire network can feel the strain. (Learn more: “Stress and Resiliency: Understanding Cortisol.”)
2. Glucose
What test to ask for: Glucose test as part of a comprehensive metabolic panel
Optimal ranges: 73 to 89 mg/dL
Your glucose levels reflect how efficiently your body converts food into usable fuel. When glucose is in a healthy range, energy feels steady, metabolism is more predictable, and your body can respond well to stress, exercise, and recovery. That’s why glucose is one of the best indicators of overall metabolic stability.
Because glucose can fluctuate throughout the day, it’s valuable to also understand how your average glucose trends over time. This is where HbA1c comes in — not as its own separate biomarker, but as one that can help you better understand the long-term effect of glucose patterns.
HbA1c (glycated hemoglobin or A1C, as it’s often referred to) shows how much glucose has been circulating over the past three months by measuring how much glucose has attached to red blood cells (a process known as glycation). Since those cells live for about 120 days, HbA1c offers a long-range view that complements day-to-day fasting glucose readings.
Why does this matter for longevity? Research shows that higher average glucose levels — even when occasional readings appear normal — is correlated with increased cardiometabolic risk and long-term health challenges.
Glucose levels that appear “normal” on paper can still be early warning signs. For instance, fasting glucose in the 90s is considered acceptable, yet evidence shows it is associated with vascular strain and a significantly greater likelihood of developing diabetes within the next decade.
Even modest increases in glucose can point to meaningful metabolic shifts, including the following:
- Impaired insulin signaling
- Increased inflammatory load
- Reduced cellular energy
- More rapid fat storage
- Higher cardiometabolic risk
Because glucose responds quickly to stress, poor sleep, hormonal changes, and nutritional choices, it is often the first biomarker to reflect subtle imbalances in metabolism. It’s also deeply interconnected with cortisol and thyroid regulation, which influence mood, energy, metabolism, and recovery. When glucose is elevated, or even slightly unstable, it can have downstream effects across multiple systems.
3. Insulin
What test to ask for: Fasted insulin test
Optimal ranges: 2.5 to 6 uiu/ml
Insulin plays a central role in how effectively your body moves glucose into cells and maintains stable energy throughout the day. When insulin is elevated, the body is working harder than it should to regulate blood sugar, often long before noticeable symptoms appear. Because insulin responds to both lifestyle and metabolic stress, it is one of the first biomarkers to reveal shifts in metabolic efficiency.
Lifestyle plays a powerful role in shaping insulin sensitivity. Stress, disrupted sleep, inactivity, and nutrient deficiencies can all weaken the body’s ability to use insulin effectively. But even small changes can make a measurable difference. A short walk after meals, balanced macronutrient timing, and improved sleep patterns can all help the body respond better.
Chronically elevated insulin can contribute to these issues:
- Weight gain, especially around the midsection
- Fatigue after meals
- Brain fog
- Increased inflammation
- Disrupted hormone production
- Higher risk of metabolic syndrome
Insulin is one of the most predictive biomarkers for long-term cardiometabolic health, and when it’s viewed alongside glucose and cortisol, it provides a window into how your metabolism is functioning and where future risks may be emerging.
4. Magnesium
What test to ask for: Red blood cell magnesium or serum magnesium
Optimal ranges: Red blood cell magnesium 5.7–6.4 mg/dL (or 5.6–6.5 mg/dL if test is from Quest Labcorp); Serum magnesium 2.2 to 2.4 mg/dL
Magnesium is one of the most essential minerals in the body and is involved in more than 300 biochemical reactions. It influences muscle function, sleep quality, blood-sugar regulation, nervous system stability, cardiovascular health, and detoxification.
But magnesium can get depleted when you’re under stress, whether from poor sleep, emotional stress, intense training, inflammation, or certain medications. This contributes to making magnesium one of the most common nutrient deficiencies, even among people who believe they are eating well or following a healthy lifestyle.
Low magnesium is often linked to the following factors:
- Ongoing stress
- Disrupted sleep
- Reduced nutrient absorption
- High training volume
- Chronic inflammation
- Suboptimal dietary intake
Early signs of low magnesium are often subtle. Fatigue, restless sleep, muscle tightness, irritability, cravings, and afternoon slumps can all indicate that the body is working harder due to inadequate magnesium. And because the nutrient supports energy metabolism, low levels can influence how cells produce and use energy throughout the day.
Magnesium status also affects glucose regulation and insulin sensitivity. Studies show that even modest increases in magnesium intake can help stabilize blood sugar, tame inflammation, and support cardiovascular health. This makes magnesium a key player in metabolic balance and long-term vitality.
Magnesium also affects multiple pathways in the body, especially those tied to energy production, recovery, inflammation control, and hormonal balance. When magnesium is adequate, the body is better equipped to maintain steady energy, manage stress, and support restorative processes.
5. Homocysteine
What test to ask for: Homocysteine test
Optimal ranges: Female 7 to 8.5 umol/liter; Male 7 to 9 umol/liter
Homocysteine is a key indicator of how efficiently your body performs methylation, a process essential for detoxification, cardiovascular health, brain function, and DNA repair. When methylation is working well, cells run smoothly and inflammation remains controlled. When it becomes inefficient, homocysteine levels rise, revealing stress at a cellular level long before symptoms emerge.
Homocysteine is highly responsive to nutrient status in the body. Elevated levels often point to deficiencies in B vitamins such as B6, B12, and folate, which support the pathways that convert homocysteine into beneficial compounds the body can use. As these nutrients become depleted, homocysteine builds up, signaling areas where support may be needed.
Imbalanced homocysteine can also be associated with the following:
- Inflammation
- Impaired detoxification
- Increased cardiovascular risk
- Increased kidney disease risk
- Increased dementia risk
Because homocysteine reflects the efficiency of methylation, changes in this biomarker often mirror changes in energy production, mood, focus, vascular health, and resilience. Elevated levels have been linked to increased oxidative stress, endothelial (cellular layer lining blood vessels) dysfunction, and cognitive decline — all of which affect long-term vitality.
Optimizing homocysteine is not just about lowering a number: It is about improving the fundamental processes that help your cells repair, protect, and regulate themselves. When methylation is strong, the body manages inflammation better, detoxifies more efficiently, and maintains healthier brain and cardiovascular function.
Homocysteine sits at the crossroads of metabolic, neurological, and cardiovascular pathways. Because it reflects nutrient status, inflammatory load, and cellular stress, it offers a powerful snapshot of underlying health — not just today, but in the years ahead.
The Bottom Line on Biomarkers
While there are many meaningful biomarkers that can inform your health, these five offer valuable insight into stress regulation, energy production, inflammation control, nutrient status, and cellular repair. Together they can start to create a clearer snapshot of how your body is functioning today and where subtle shifts may be happening beneath the surface.
You can ask your healthcare provider to test these biomarkers or explore direct-to-consumer or precision-care options. These biomarkers — plus 65-plus other ones — are tested at MIORA, the personalized, precision medicine clinics located within select Life Time athletic country clubs.
Unlike direct-to-consumer labs, which often email you a report to decipher on your own, MIORA is rooted in the Metabolic Code, a program I developed to combine symptomology, biometrics, comprehensive bloodwork, and the expertise of real medical providers to help interpret your results in context. The insights from your biomarkers are translated into a personalized action plan, supported by ongoing communication and clinical oversight.
The goal is not just to collect numbers, but to guide meaningful, medically informed steps that help you move forward with confidence.
The first draft of this article was edited using an artificial intelligence tool; it was finalized via the Life Time Editorial review process, which includes multiple rounds of editing and refinement.
