It is estimated that people with type 1 diabetes (T1D) make hundreds of health-related decisions every day – What’s my blood glucose? How many carbohydrates are in this? How much insulin do I need? The ability to problem solve and think critically is paramount to managing the complexities of T1D, and it’s safe to say that all of this constant planning and decision-making takes a lot of brainpower!

Unfortunately, people with T1D and type 2 diabetes are at increased risk for dementia, characterized by impaired cognitive functioning in areas such as memory, problem-solving, and information processing. A 2015 study found that people with T1D were 83% more likely to develop dementia as older adults.

So what can you do to reduce your risk of developing dementia? First, let’s look at the presentation and risk factors for cognitive decline in T1D, then review strategies, such as managing blood glucose (BG) levels, nutrition, and other lifestyle factors that can help prevent or delay cognitive decline.

Cognitive Decline in T1D: Presentation and Risk Factors

Research suggests that minor cognitive impairments present soon after a T1D diagnosis but remain relatively stable over time, with adequate BG management. Modest cognitive decline is generally seen in adults who have had diabetes for 25 years or more. Slowed information processing, decreased attention, mental flexibility, and executive functioning seem to be the most significant cognitive deficits, while memory, luckily, seems to be spared. The severity of cognitive decline is associated with the age of onset and duration of diabetes. Specifically, people diagnosed with T1D between the ages of 5 and 7 seem to be at higher risk for cognitive decline, likely due to experiencing extremely high BG at a critical time of childhood brain development.

Common diabetes complications, such as retinopathy, polyneuropathy, and kidney disease have been linked to cognitive decline. Since these complications are all microvascular in nature, this suggests that microvascular disease in the brain, a consequence of hyperglycemia, is the main cause of cognitive decline in people with diabetes.


Hyperglycemia, or high BG, damages the small blood vessels of the body and can result in microvascular disease over time. Hyperglycemia also causes oxidative stress and inflammation in the brain, which can damage brain cells.


Episodes of recurrent hypoglycemia, or low BG, do not seem to impair cognitive function in young adults but may affect adults over the age of 50 (Duinkerken, 2020). One study found that older adults who experienced hypoglycemia were 66% more likely to develop dementia than those who didn’t during a 7-year period.

BG Goals

So, what BG range should you aim for? Research shows that people with T1D who increase their time in a target BG range of 70-180mg/dL had decreased risk for microvascular complications. One source suggests that people with T1D who have long-term glycated hemoglobin (HbA1c) <7.9% can reduce their risk for dementia, while another study suggests that maintaining an HbA1c ≤ 7.5% is desirable to prevent cognitive decline. Discuss your individual risk factors and BG goals with your healthcare providers.

Nutrition and Cognitive Health

While managing BG seems to be the most crucial factor when it comes to cognitive health in diabetes, nutrition (far beyond carb counting) plays a role. Diets high in fat and refined sugars can contribute to dementia, while diets rich in fruits, vegetables, and fish may help prevent or delay cognitive decline. While studies analyzing the effects of certain diets on brain health in T1D subjects are lacking, the Mediterranean diet is associated with a lower risk for dementia, and the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet is associated with a slower rate of cognitive decline. Without elaborating on these eating patterns, both are rich in antioxidants that can help fight damage caused by inflammation and oxidative stress from hyperglycemia.

Foods to Include

The Mediterranean and MIND diets emphasize eating fruits and vegetables (especially berries and leafy greens), fish and seafood, nuts and seeds, legumes, whole grains, and healthy fats. While more research is needed in T1D subjects, fish, flavonoids, and the antioxidants lutein and lignan seem to be particularly valuable when it comes to cognitive health; here are a few foods to include:

  • Berries
    Berries are rich in flavonoids and lignans, which have been linked to cognitive health. Berries are also a good source of fiber and have a low glycemic index to help balance BG levels. Research shows that eating blueberries and strawberries on a regular basis is associated with slower rates of cognitive decline. Try adding berries to oatmeal, cereal, yogurt, and smoothies or pairing with nuts for a nutrient-rich snack.
  • Leafy Greens
    Leafy greens, such as spinach, collard greens, and kale are rich sources of lutein and other antioxidants. Lutein accumulates in the brain and can help reduce inflammation. Research suggests that adding a daily serving of leafy greens to your diet may help preserve cognitive function. Try adding leafy greens to soups and stews, salads, omelets, smoothies, or as a sauteed side dish to a meal.
  • Fish
    Oily fish such as salmon, herring, and albacore tuna are excellent sources of the omega-3 fatty acids that support healthy brain function. Studies show that eating at least two servings of fish per week may reduce your risk for dementia.
  • Nuts and Seeds
    Walnuts are notorious for their “brain-boosting” power, but other nuts and seeds may also help preserve cognitive function. Flax, pumpkin, and sesame seeds, for example, are excellent sources of lignans, which have been associated with less cognitive decline. Nuts and seeds also offer healthy fats and fiber to help balance blood sugars and satisfy hunger.

Vitamin B12 Deficiency

Vitamin B12 deficiency is a well-known cause of cognitive decline. You’re at particularly high risk for B12 deficiency if you are vegan or vegetarian, take certain medications such as Metformin, or proton pump inhibitors for acid reflux, or if you are over the age of 60. If you fall into this high-risk category, consider asking your healthcare provider to check your B12 level during your next checkup.

Other Modifiable Risk Factors

Here are other steps you can take to reduce your risk for cognitive decline:

  • Engage in regular physical activity
  • Quit smoking
  • Manage blood pressure
  • Address depression
  • Participate in mentally or socially stimulating activities.


People with T1D are at higher risk for developing cognitive decline and dementia. Prolonged hyperglycemia and episodes of hypoglycemia in people over the age of 50 increase the risk of cognitive decline. Achieving a long-term HbA1c of less than 7.5-7.9% and improving your time-in-range BG (70-180mg/dL) can reduce the risk for microvascular disease and associated cognitive decline. Additionally, a balanced diet that regularly includes berries, leafy greens, fish, nuts, and seeds may help prevent or delay cognitive decline. Talk to your healthcare providers about your individual BG goals and strategies you can implement to keep your T1D brain healthy.