Type 2 diabetes is often discussed through blood glucose, weight, A1c, blood pressure, or cholesterol. Those measures matter. But people living with diabetes are also asking a broader question: What does metabolic health mean for the brain over time?

Brain health belongs in the type 2 diabetes conversation

That question has become more urgent as new research links diabetes-related traits with cognitive outcomes. Two recent studies add useful information. One compared diabetes medication regimens and recorded cognitive diagnoses in a large U.S. electronic-health-record database. The other used genetic methods to examine whether a lifelong predisposition to higher glucose after a glucose challenge might be related to Alzheimer disease risk.

Both studies are worth understanding. Neither should be read as a reason to change medication without clinical guidance, fear insulin, or assume that one “blood sugar spike” causes dementia.

The large medication study: important associations, not treatment instructions

A 2026 PLOS ONE retrospective cohort study used the TriNetX U.S. Collaborative Network to examine electronic health records from more than 1.5 million adults aged 40 to 69 with type 2 diabetes. Researchers compared people using metformin alone with people using metformin plus a DPP-4 inhibitor, GLP-1 receptor agonist, or SGLT-2 inhibitor, as well as a separate group using insulin alone.

After propensity-score matching, the investigators reported that metformin plus a GLP-1 receptor agonist was associated with lower recorded incidence of mild cognitive disorder, Alzheimer disease, and vascular dementia than metformin alone. Metformin plus an SGLT-2 inhibitor was associated with lower recorded incidence of vascular dementia, but not the other cognitive outcomes. Insulin monotherapy was associated with higher recorded incidence of all three outcomes.

The word associated is doing important work here.

This was not a randomized trial in which people were assigned to one medication and then followed to see whether that treatment prevented dementia. It was an observational analysis of records from people already receiving different regimens. Even with matching, groups can differ in ways that are difficult to fully measure in electronic records.

The authors explicitly caution that the insulin findings should not be interpreted as a direct drug effect. People prescribed insulin alone may have had longer-standing or more severe diabetes, more complications, more kidney or cardiovascular disease, different access to care, or other factors that increase cognitive risk. The authors also noted differences in mortality and follow-up that can affect how cause-specific hazard ratios are interpreted.

The study does not show that insulin causes dementia, that GLP-1 medicines prevent Alzheimer disease, or that anyone should switch medication to protect their brain.

It does reinforce a sensible research question: whether glucose-lowering therapies that improve cardiometabolic risk could also be related to long-term brain health. That question needs randomized trials and longer-term evidence before it becomes a medication-selection rule.

The post-meal glucose study: a genetic clue, not a dietary verdict

A separate UK Biobank study published in Diabetes, Obesity and Metabolism examined genetic variants associated with insulin resistance, fasting insulin, fasting glucose, and two-hour post-load glucose. This method, called Mendelian randomization, uses inherited genetic variation as a tool to explore whether an exposure may plausibly contribute to an outcome.

In up to 357,883 White British UK Biobank participants, genetically predicted higher two-hour post-load glucose was associated with a 69% higher odds of Alzheimer dementia. The study did not find evidence that fasting glucose, fasting insulin, or postprandial glucose influenced total brain, hippocampal, or white-matter-hyperintensity volumes.

The result is interesting, but the caveat is just as important: the Alzheimer association did not replicate in the independent Alzheimer genome-wide association study used by the authors. The researchers concluded that replication in other populations and ancestries is needed to clarify the finding and its mechanisms.

That limitation should change how the study is communicated. It is inaccurate to say the research proved refined carbohydrates are “neurotoxic,” that a single post-meal rise in glucose causes Alzheimer disease, or that avoiding a particular food guarantees brain protection. The analysis addressed genetic predisposition to higher post-load glucose, not a real-time continuous-glucose-monitor reading after a specific breakfast.

The study does, however, add to a larger body of work showing that metabolic health, vascular health, and brain health are connected. That is a reason to take blood-glucose management seriously—not a reason to panic about food.

What supports brain health now?

The practical foundation is not a single medicine, food, supplement, or wearable metric. It is a comprehensive plan that addresses the factors most likely to affect health across the body.

For people with type 2 diabetes, that commonly means working with a care team on individualized glucose management; blood-pressure and cholesterol control; smoking cessation when relevant; physical activity; sleep; nutrition; social connection; mental-health support; and regular review of medications and complications. These areas overlap. Improving cardiovascular and kidney risk can also support the health of the blood vessels that supply the brain.

Food matters, but a helpful food strategy should be sustainable rather than fear-based. Many people benefit from meals that emphasize minimally processed foods, fiber-rich carbohydrates, vegetables, legumes, protein sources, and fats that support satiety. Pairing carbohydrate-containing foods with protein, fiber, or fat may help some people reduce the size or speed of their glucose rise.

Movement is another brain-and-metabolic-health tool. Aerobic activity and resistance training can improve fitness, strength, insulin sensitivity, and glucose management. Sleep deserves similar attention, especially when snoring, witnessed breathing pauses, insomnia, daytime sleepiness, or fatigue are present.

Questions to bring to a clinician

If brain health is a concern, consider asking: Is my glucose-management plan meeting my current needs? Are my blood pressure, cholesterol, sleep, and cardiovascular risks being addressed? Could any medications affect my cognition, sleep, or hypoglycemia risk? Should I be screened for sleep apnea or depression? What kind of activity plan is safe and realistic for me?

These questions are more useful than trying to identify one “perfect” medication or one prohibited food. They move the conversation toward prevention, monitoring, and practical support.

Diabetes Reversal Group believes type 2 diabetes care is strongest when it addresses the whole person—food, movement, sleep, stress, support systems, and ongoing clinical monitoring. For some people, clinician-directed medication is an important part of that plan; for everyone, lasting health requires more than a prescription alone.

By: Dr. Jeffrey Hockings, CEO & Founder & Kristine Burke, MD, Chief Medical Officer

Do not start, stop, or change diabetes medication without guidance from the clinician managing your care.