Normal Blood Sugar Isn't the Whole Story: Metabolic Health Explained

Part four in our series on Susan Earl Functional Health’s eight health pathways.

If your fasting glucose and A1c are in range, that is reassuring about the blood sugar measured by those tests. But it does not tell you everything about how your body is responding to insulin, or about your overall metabolic health.

That distinction can matter when you have been told your numbers look fine but still feel concerned about weight that will not shift, low energy, or a family history of metabolic and cardiovascular problems. It does not mean you have a hidden condition. It means one or two results cannot answer every question.

What blood sugar tests tell you, and what they don’t

Fasting glucose is a snapshot of the glucose in your blood after you have not eaten for a period of time. A1c estimates average blood glucose over roughly the past two to three months. Both are useful, established tools for identifying diabetes and elevated blood sugar.

The American Diabetes Association’s 2026 Standards of Care define prediabetes using measures such as an A1c of 5.7%–6.4% or fasting glucose of 100–125 mg/dL. Results below those ranges may be reassuring, but neither test directly measures how sensitive your cells are to insulin.

Insulin helps move glucose from the bloodstream into cells. When cells respond less effectively, the pancreas may release more insulin to help keep glucose within range. This compensation can happen for a time, so a person’s glucose results may remain below the thresholds for prediabetes even as other aspects of metabolism deserve attention.

In other words, a normal glucose result is not proof that insulin resistance is absent. But it is important not to leap from that possibility to a diagnosis. Insulin resistance is not determined by one symptom, one lab value, or a popular online checklist.

Why the broader pattern matters

Metabolic health is shaped by a mix of factors. A provider may consider blood pressure, cholesterol and triglycerides, waist measurement, family history, activity, sleep, medications, and other health information alongside glucose results. Depending on the person, they may also discuss whether additional testing is appropriate.

Some measures, such as fasting insulin or calculated HOMA-IR, are used in research or selected clinical settings to estimate insulin resistance. They are not universal stand-alone diagnostic tests, and cutoffs are not standardized for every purpose. Any testing decisions should be made with your healthcare provider, who can interpret results in context.

A1c also has limitations. It estimates average blood glucose; it does not directly show insulin levels or every rise and fall in blood sugar. In some circumstances, including conditions that affect red blood cells, A1c may not reflect glucose accurately. The ADA advises clinicians to consider potential interference when A1c and other results do not agree.

And weight that will not move is not proof of insulin resistance. Weight can be influenced by many factors, including sleep, stress, medications, health conditions, environment, and life changes. The goal is not to label yourself from a symptom. It is to build a more complete and useful conversation with your provider.

What research says about insulin resistance and cardiovascular health

Insulin resistance is considered an important part of cardiometabolic risk. Researchers have studied whether it may contribute to cardiovascular problems even before a person develops diabetes. The evidence is meaningful, but it does not show that insulin resistance alone causes heart disease in everyone.

In a 15-year study of 919 adults without cardiovascular disease at the start, researchers found that participants with higher estimated insulin resistance had a greater likelihood of a first cardiovascular event. The study used HOMA-IR, a measure calculated from fasting glucose and insulin. Its findings support an association, but, as an observational study, it cannot prove that insulin resistance caused those events or rule out every other influence. Read the study: Bonora et al., Diabetes Care.

A separate study followed people who already had arterial disease but did not have known diabetes. Higher HOMA-IR was associated with more cardiovascular events in this higher-risk group. That result adds to the research, but it should not be assumed to predict the same level of risk for a person without known arterial disease. See the SMART study.

Insulin resistance may be one part of a wider pattern involving blood pressure, blood fats, inflammation, and body-fat distribution. These factors often overlap, which makes cause and effect difficult to separate. It is more accurate to call insulin resistance a possible upstream contributor and a useful area of study, not the sole explanation for cardiovascular risk.

What researchers are learning about insulin resistance and cognition

Studies have also explored connections between insulin resistance and cognitive performance. That research is still developing, and an association does not mean that insulin resistance inevitably leads to memory loss or dementia.

A prospective community study of older Korean adults found that changes in estimated insulin resistance were associated with cognitive decline among participants with normal cognitive function at baseline. Only a subset of the original group had repeated cognitive testing, and the findings do not establish that insulin resistance caused the decline. Read the study in Scientific Reports.

In another study, higher estimated insulin resistance in late-middle-aged adults was associated with differences in brain volume and memory performance. The researchers noted limitations, including a smaller group for follow-up brain imaging. Read the study in Journal of Alzheimer’s Disease.

These findings give researchers reasons to keep studying metabolic health and the brain. They are not proof that an individual’s brain fog is caused by insulin resistance, or that changing a single lab result will prevent cognitive decline.

Practical steps that support metabolic health

You do not need to make dramatic changes, or assume something is wrong, to take a thoughtful approach to metabolic health. Small habits that fit your life can be a reasonable place to start:

• Build meals that satisfy you. Include a mix of foods such as vegetables, beans or other sources of fiber, protein, and whole grains, according to your needs and preferences.
• Find movement you can repeat. Walking, strength-building activity, or another enjoyable form of movement can support overall health. Start at a level that is appropriate for you.
• Make sleep part of the conversation. If you sleep poorly, snore, or wake feeling unrefreshed, tell your provider. Sleep can affect health in many ways.
• Look for patterns, not perfection. Notice what is realistic in your schedule and what helps you feel well. Consistency matters more than a short-lived burst of effort.
• Discuss concerns with your provider. Ask what your current results do and do not tell you, and whether any further assessment makes sense for your history.

Making sense of your results with support

Susan Earl, RN, brings 43 years of cardiology and emergency nursing experience to her health coaching and education practice. That background informs her perspective on the patterns that may be worth discussing, not just one number viewed on its own.

Susan can suggest which lab work to discuss with your provider and assess or review results with you in an educational coaching context. She does not order or run labs, diagnose conditions, prescribe treatment, or replace your healthcare provider. Her coaching is designed to help you understand your questions and build practical habits. It is not medical care. The RN credential and scope language are grounded in the North Carolina Board of Nursing’s RN Scope of Practice. Clarification.

Normal fasting glucose and A1c are useful information. They are not the whole story of your metabolism, and they do not need to be treated as a reason to panic. If you still have questions, bring them to your provider and ask what the full pattern means for you.

Free 5-minute clarity call

If you would like to explore whether health coaching and education may be a fit, schedule a free 5-minute clarity call with Susan. This is a brief conversation about your goals and the coaching approach, not a medical consultation or a substitute for care from your provider.