Sugar, Insulin, and the Aging Body

Nearly 29 percent of Americans over 65 have diabetes. Another 52 percent have prediabetes. If you are reading this, there is roughly an 80 percent chance that one of those numbers applies to you.

Those figures, from the CDC’s January 2026 National Diabetes Statistics Report, describe a condition so common among older Americans that it functions less like a diagnosis and more like a default setting. Forty million people across all ages. A disease that accounts for 25 percent of all healthcare spending in the country. Medical costs for people with diabetes more than double those of people without it.

But the numbers do not capture what makes type 2 diabetes so dangerous after 60. The danger is not the blood sugar itself. It is what sustained insulin resistance does to everything else.

The Metabolic Cascade

Type 2 diabetes in older adults is not a single disease. It is a metabolic accelerant. The elevated glucose and insulin resistance that define it damage blood vessels, nerves, and organs through overlapping pathways that compound over time.

Cardiovascular disease is the leading cause of death among people with diabetes. The risk is not modestly elevated; it is roughly doubled, and among older adults the relationship is even more pronounced. Chronic kidney disease progresses faster. Peripheral neuropathy, the numbness and tingling that often begins in the feet, affects more than half of people with longstanding diabetes and is a primary contributor to falls (a subject installment 3D will examine in detail). Retinopathy threatens vision. Wound healing slows. Infections become more frequent and harder to resolve.

Each of these complications is serious on its own. In an older adult managing three or four of them simultaneously, they interact. The kidney decline changes which medications are safe. The neuropathy changes which exercise is possible. The cardiovascular risk changes every clinical decision. Diabetes in a 68-year-old is not the same disease it was at 48. It has had twenty additional years to erode the systems that keep the body stable.

And then there is the brain.

A growing number of studies over the past decade have confirmed what clinicians suspected: type 2 diabetes significantly increases the risk of cognitive decline and dementia, including Alzheimer’s disease. The pathways include vascular damage to small cerebral blood vessels, chronic inflammation that crosses the blood-brain barrier, and insulin resistance in the brain itself, which disrupts neuronal signaling and may accelerate amyloid plaque accumulation. Some researchers have informally called Alzheimer’s “type 3 diabetes,” a label that oversimplifies the relationship but captures a real biological connection.

This means that for the 29 percent of older Americans with diabetes, the disease is not only damaging their kidneys, hearts, nerves, and eyes. It may also be damaging their brains. And for most of them, that conversation has never happened in a doctor’s office.

The GLP-1 Revolution and Its Limits

This is where the story gets complicated, and where honest reporting requires holding two truths at the same time.

GLP-1 receptor agonists, the class of drugs that includes semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound), have transformed diabetes and obesity treatment. They work by mimicking a gut hormone that promotes insulin secretion, suppresses appetite, and slows gastric emptying. Their effects on blood sugar, body weight, and cardiovascular outcomes are well established.

In 2025, a series of large observational studies reported that people with diabetes who took GLP-1 drugs developed dementia at dramatically lower rates than those on other diabetes medications. A JAMA Neurology meta-analysis pooling data from 26 clinical trials involving more than 160,000 people with type 2 diabetes found a 45 percent reduction in dementia risk. A Lancet study using global electronic health records from over 82,000 matched patients found a 42 percent reduction (hazard ratio 0.58). Other cohort studies reported reductions as high as 70 percent.

These are striking numbers. They suggest that GLP-1 drugs may offer meaningful neuroprotection for people with diabetes, likely through a combination of improved metabolic control, reduced inflammation, better vascular health, and possibly direct effects on brain insulin signaling.

But here is the other truth.

In November 2025, Novo Nordisk announced the results of EVOKE and EVOKE+, two large Phase 3 trials that tested oral semaglutide in people who already had early-stage Alzheimer’s disease. The trials enrolled 3,808 participants across 40 countries. They were the largest, longest GLP-1 trials ever conducted in a neurodegenerative disease.

Semaglutide did not slow cognitive decline. On the primary measure, the Clinical Dementia Rating scale, the drug performed no better than placebo. It did improve some biomarkers linked to neuroinflammation, reducing them by roughly 10 percent, but that improvement was too small to translate into a clinical benefit. Novo Nordisk discontinued the planned one-year extension.

The distinction matters enormously. GLP-1 drugs appear to protect against developing dementia in people whose metabolic dysfunction is driving brain damage. But once Alzheimer’s disease has taken hold, the metabolic intervention alone is not enough to reverse or slow it. Prevention and treatment are different problems.

Frank, Sitting at the Kitchen Table

Frank is 68. He was diagnosed with type 2 diabetes fifteen years ago. His A1C has been stable in the low sevens for most of that time, which his doctor calls “well controlled.” He takes metformin and a statin. His blood pressure is managed. By most clinical measures, he is doing fine.

But his kidney function has been slowly declining for three years. His feet are numb enough that he cannot always tell when he has a blister. He has gained weight that his doctor periodically mentions but has no practical plan to address in an eight-minute visit. Nobody has ever told him that his diabetes may be affecting his brain. Nobody has ever mentioned GLP-1 drugs to him, even though the evidence for cardiovascular and renal protection in his age group is strong and the emerging data on cognitive protection is striking.

Frank is not unusual. He is typical. The gap between what the evidence supports and what most older adults with diabetes actually receive is one of the widest in American medicine.

The Cost and Access Problem

GLP-1 drugs work. The evidence is increasingly clear across cardiovascular, renal, metabolic, and potentially neurological domains. The problem is who can get them.

Until recently, Medicare did not cover GLP-1 drugs prescribed for weight management, only for diabetes and, since 2024, for cardiovascular disease. The Trump administration’s BALANCE model, announced in late 2025, is designed to change that. A Medicare GLP-1 payment demonstration launching in July 2026 will offer qualifying beneficiaries access to these drugs at $50 per month. The full BALANCE model will begin in Medicare Part D in January 2027 and in participating state Medicaid programs as early as May 2026.

The negotiated price for injectable GLP-1s under the program is $245 per month, which will decrease over a two-year period. These are significant reductions from list prices that have exceeded $1,000 monthly. But $245 per month, even $50 per month for copays, remains a barrier for many older Americans on fixed incomes. And the program’s voluntary structure means that coverage will depend on participation by drug manufacturers, states, and Part D sponsors. It is not a guarantee.

Meanwhile, prescribing disparities persist. Black and Hispanic Americans have substantially higher rates of diabetes but lower rates of GLP-1 prescription. The reasons are structural: insurance coverage differences, provider prescribing patterns, pharmacy access, and the cost barriers that fall hardest on communities already carrying the greatest disease burden.

The BALANCE model is a meaningful step. Whether it is sufficient depends entirely on implementation, and on whether the communities with the highest diabetes prevalence actually gain access to the drugs with the strongest evidence.

The Prevention Nobody Prescribes

Here is what Frank’s doctor knows but does not have time to say: the most effective interventions for type 2 diabetes in older adults are not primarily pharmaceutical. They are dietary modification and physical activity.

The evidence is not subtle. Structured exercise programs improve insulin sensitivity, reduce A1C, lower cardiovascular risk, preserve kidney function, and improve the neuropathy symptoms that make daily life harder. Dietary changes that reduce processed carbohydrates and increase fiber, lean protein, and whole foods produce measurable metabolic improvement within weeks. Combined, diet and exercise can reduce the risk of progressing from prediabetes to diabetes by nearly 60 percent, a finding from the Diabetes Prevention Program that has been replicated repeatedly.

But prescribing exercise is not like prescribing metformin. There is no pharmacy that fills it. There is no insurance code that reliably covers it. There is no monitoring system that tracks adherence. A doctor can write a prescription for a statin in ninety seconds and be confident that the patient will receive it. Telling a 68-year-old with numb feet and a bad knee to “exercise more” without a referral to physical therapy, a structured program, or any follow-up is not a prescription. It is a suggestion, and suggestions have a poor track record.

Medicare limits the number of physical therapy visits it covers. SilverSneakers, the most widely available exercise program for seniors, depends on Medicare Advantage plan participation and is not available to all beneficiaries. Community-based diabetes prevention programs exist but are inconsistently funded and hard to find. The infrastructure for the single most effective intervention in diabetes management barely exists.

What This Means for You

If you have type 2 diabetes and you are over 60, your disease is doing more than affecting your blood sugar. It is affecting your blood vessels, your kidneys, your nerves, your eyes, and quite possibly your brain. That is not a reason for despair. It is a reason for a longer conversation with your doctor.

Ask whether a GLP-1 drug is appropriate for you. Not because it is new, not because it is popular, but because the evidence for cardiovascular and renal protection is strong and the evidence for cognitive protection is growing. If cost is a barrier, the BALANCE program launching in mid-2026 may change the math.

Ask about your kidneys. Ask about your feet. Ask about cognitive screening, which Series 2 of this publication covers in depth.

And know this: the body’s response to diabetes at 68 is not fixed. Metabolic health can improve at any age. The interventions that move it most are the ones that require no prescription: how you eat and how you move. The final installment of this series will make the full case for movement as medicine. But for people living with diabetes, the case starts here: insulin sensitivity improves with exercise at every age tested. The body after 60 is not done responding. It is waiting to be asked.