Your brain runs on glucose, but too much or too little can affect your thinking. Research reveals a sweet spot for blood sugar control that offers the best protection for your brain. 

People living with diabetes develop dementia more often than people without diabetes. And the pattern shows up across different types of dementia, not only Alzheimer’s disease. Researchers are finding that glucose control and brain health go hand-in-hand.

It’s not only high sugars that cause trouble. Very low sugars can strain the brain, too. In that same line of research, people who experienced severe hypoglycemia had a higher risk of cognitive problems later. That is one reason why many clinicians aim for safe, steady targets rather than the lowest number possible. 

A large primary-care study in Hong Kong backs up that diabetes may affect your memory. The scientists followed participants for years and observed that adults had the lowest dementia risk when their long-term A1C (a blood test that measures blood sugar) averaged in the moderate range, roughly 6.5% to 7.5%. Risk increased when A1C ran higher. Dementia probability also crept up when average A1C dipped lower, likely reflecting the harms of glucose swings and low episodes. Risk was lowest with steady control, not extremes. 

Why might diabetes affect memory? Scientists point to overlapping pathways. Insulin resistance can interfere with how brain cells use energy. High sugars can damage small blood vessels that feed memory areas, leading to inflammation build-up over time. None of this means dementia is certain. Instead, it’s a reminder to work on blood sugar and brain health side by side.

Medicines May Help Both Metabolism and Memory 

Modern diabetes medicines do more than lower A1C. According to a recent observational review, long-term metformin use may be linked with lower dementia risk, especially with earlier and consistent use. Beyond improving insulin sensitivity, metformin has anti-inflammatory properties and may even affect cellular aging pathways, which could also contribute to brain protection.

In addition, reviews of some medications that mimic a natural gut hormone called GLP-1, such as liraglutide, suggest possible brain benefits. In real-world reports, people taking these medicines had slower cognitive decline and lower rates of dementia than people on other diabetes drugs. Researchers think these medicines may reduce brain inflammation and improve insulin signaling in the brain. 

Large population reports echo this pattern. In analyses of millions of adults, GLP-1 medicines were associated with lower rates of Alzheimer’s and vascular dementia. Another study in JAMA Neurology found that both GLP-1 medicines and SGLT2 inhibitors, meds that help your kidneys remove glucose through urine, may be linked to lower incident dementia when compared with other diabetes treatments. These findings show associations, not proof, but they point in a hopeful direction. 

What about people who already have memory loss? Early clinical trials in people with established Alzheimer’s disease show mixed results so far. That tells us that the best window of opportunity to make an impact may be earlier, when we are preventing or delaying changes rather than trying to reverse established disease. Talk with your clinician about whether—and when—these medicines may fit your overall care plan. 

Steady Glucose Supports Memory 

Healthy blood vessels support a healthy brain. That same study in Hong Kong found that steady, mid-range A1C tracked with lower dementia risk, especially vascular dementia, which is driven by blood vessel changes in the brain. Keeping blood pressure in range can ease strain on small brain vessels.

The same habits that help the heart also help the brain. You likely know many of them: keep glucose steady, manage blood pressure and cholesterol, and keep moving. Do what you can to avoid big swings and prevent lows. Your care team can help you set safe glucose targets that match your life. 

Simple Moves That Lower Dementia Risk 

Here are ideas to consider adding to your routine. Share them with your clinician before changing medicines or goals. 

  • Aim for steady, moderate A1C as individualized with your clinician; some older adults do well with mid-6s to mid-7s (as noted in cohort data). Avoid frequent lows. 
  • Ask about modern meds, if needed. If diet, activity, and metformin are not enough, ask your doctor about GLP-1 receptor agonists or SGLT2 inhibitors. Recent studies are hopeful, in that they associate both classes with lower dementia risk and strong cardiovascular benefits. 
  • Move most days. Try 20 to 30 minutes of brisk walking, water exercise, chair routines, or light strength work. Movement improves insulin sensitivity and blood flow to the brain. 
  • Eat for your heart and brain. Fill your plate with vegetables, beans, fish, nuts, and olive oil. Cut back on refined carbs and sugary drinks. Small swaps add up. 
  • Prevent lows. Keep regular meals and snacks, know your symptoms, and carry a quick source of glucose. Ask your clinician if a continuous glucose monitor could help you stay safe. 
  • Use team-based care. Primary care providers, pharmacists, and dietitians can help you set goals, adjust medicines, and stay on track. 

Steady habits, paired with the right care plan, can help you manage your blood sugar and protect your brain. Remember, diabetes may affect your memory. Keep them going and talk to your doctor about newer medicines that may help. 

For memory questions, a simple screening can point you toward next steps. Contact Charter Research for a free memory screen and to learn about all the studies now open. 

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