Brain-Glucose Link Explained: Doctor Explains How Diabetes Raises Alzheimer's Risk

Growing older often brings subtle changes, occasional forgetfulness or slower recall. But when memory loss becomes persistent and begins interfering with daily life, it may signal something more serious, including Alzheimer's disease. According to the World Health Organization (WHO), more than 55 million people worldwide are living with dementia, with Alzheimer's disease being the most common cause. In India, the burden is rising steadily with population ageing. At the same time, the country is also witnessing a diabetes epidemic. The International Diabetes Federation estimates that over 100 million adults in India live with diabetes. Scientists are increasingly examining how these two public health crises intersect.

Emerging research suggests that insulin resistance and blood sugar instability may play a direct role in cognitive decline. Some experts even refer to Alzheimer's as "Type 3 diabetes" due to the brain's impaired insulin signalling.

"We now understand that blood sugar variability, particularly in older adults, can negatively impact brain health," says Dr Anu Mathew, Endocrinologist, Fortis Hospital, Manesar, NCR, Delhi. "Continuous glucose monitoring allows us to track and manage those fluctuations more precisely, offering a chance for early intervention."

Is Alzheimer's Linked To Diabetes?

Several large-scale studies show that people with Type 2 diabetes have a significantly higher risk of developing Alzheimer's disease. According to the National Institute on Aging, insulin resistance, a hallmark of Type 2 diabetes, may impair the brain's ability to use glucose effectively, leading to neuronal damage over time.

Research published in journals indexed by the National Library of Medicine has found that insulin plays a critical role in memory formation and synaptic function. When insulin signalling in the brain becomes dysfunctional, it may accelerate the processes associated with Alzheimer's.

People with Type 1 diabetes are also vulnerable. Long-term glucose fluctuations can affect cognitive processing speed and memory, particularly in older adults.

Also Read: Type 5 Diabetes: Doctor Explains The Causes And Complications Of This Condition

How Blood Sugar Spikes Affect The Brain

Chronic high blood sugar can trigger inflammation, oxidative stress and vascular damage, all of which harm brain tissue. Studies cited by the Alzheimer's Association suggest that hyperglycaemia may promote the accumulation of beta-amyloid plaques, one of the defining features of Alzheimer's disease. These plaques disrupt communication between neurons and contribute to progressive cognitive decline. This biological overlap is one reason some scientists describe Alzheimer's as "Type 3 diabetes."

Dr Mathew explains, "Blood sugar variability, especially repeated spikes and crashes, may contribute to cognitive stress. Tracking these patterns gives us valuable insights that were not possible before."

Where CGM (Continuous Glucose Monitoring) Comes In

Continuous Glucose Monitoring (CGM) systems track glucose levels in real time, offering a dynamic picture of how food, sleep, stress and physical activity affect blood sugar. "CGMs also allow you to set optional alarms that alert you when glucose levels are too low or too high, enabling faster, safer action," says Dr Mathew. "These insights give us a chance for early intervention that may help slow the cognitive effects of insulin resistance in the brain."

Beyond individual tracking, CGM devices enable remote data sharing with caregivers and doctors, a feature particularly useful for older adults or individuals experiencing early cognitive symptoms. Dr Vivek Iyer, Head of Medical Affairs for Abbott's diabetes care business in South Asia, adds, "Smart technology like CGMs is transforming diabetes care. It builds vital connections between patients, caregivers and healthcare professionals. Even when someone is managing diabetes remotely or facing memory challenges, their support network can stay informed and act quickly." Real-time connectivity may prevent severe hypoglycaemia or hyperglycaemia, both of which can acutely impair cognitive function.

Diet And Lifestyle: Supporting Brain And Metabolic Health

Dietary patterns also play a major role in stabilising glucose and supporting cognitive function. The MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay), studied extensively by researchers and published in peer-reviewed journals indexed by the National Library of Medicine, combines leafy greens, berries, whole grains, legumes and healthy fats. This diet has been associated with slower cognitive decline and reduced Alzheimer's risk.

Stable glucose levels are supported by:

• High-fibre vegetables and whole grains
• Lean proteins and plant-based fats
• Reduced intake of refined carbohydrates
• Regular physical activity

The World Health Organization recommends at least 150 minutes of moderate physical activity weekly to reduce both diabetes and dementia risk.

Also Read: Mind Workouts That Boost Memory And Reduce The Chances Of Alzheimer's

Early Monitoring May Offer Hope

While there is currently no cure for Alzheimer's disease, early prevention strategies matter. Research shows that mid-life metabolic health strongly influences late-life cognitive outcomes.

"Monitoring glucose patterns through CGM, paired with dietary changes and physical activity, empowers families to take control," says Dr Mathew. "Managing blood sugar is about far more than preventing diabetes complications, it's about preserving brain function and independence." Experts emphasise that CGM should be used under medical guidance and as part of a comprehensive diabetes management plan.

The growing body of evidence linking diabetes and Alzheimer's disease highlights a critical truth, that brain health and metabolic health are deeply interconnected. Insulin resistance, chronic inflammation and blood sugar instability may quietly accelerate cognitive decline. Continuous glucose monitoring offers a powerful new tool, not just for diabetes management, but potentially for protecting long-term brain function. Combined with evidence-based dietary patterns and lifestyle modifications, proactive glucose management may help reduce the dual burden of diabetes and dementia.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.