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What’s the Connection Between Diabetes and Alzheimer’s Disease?

Alzheimer’s disease is connected to diabetes in some surprising ways. Here’s what you need to know about the link between these two conditions.
The content in this article should not be taken as medical advice. Please consult with your healthcare provider regarding your individual health needs.
Around 730,000 Canadians are living with Alzheimer’s disease or another condition that causes dementia.1 Alzheimer’s is more likely to affect people 65 years and older, but it’s not a normal part of aging.2 Recent research has found that the underlying causes of diabetes and Alzheimer’s disease are connected. Both individuals living with type 1 diabetes (T1D) and type 2 diabetes (T2D) may be at higher risk of experiencing Alzheimer’s disease or another form of dementia.
Alzheimer’s Disease vs. Dementia
Alzheimer’s disease is a type of neurodegenerative disorder, which is a condition that damages the brain. Dementia refers to a set of symptoms, such as a decline in cognitive ability, memory, and changes in behaviour, that result from conditions that affect the way the brain works. Alzheimer’s disease causes people to experience dementia.3-6 Other causes of dementia include vascular dementia, which happens when there is a reduction in blood flow to the brain—usually from a stroke—that damages the neurons, and mixed dementia, which happens due to a combination of Alzheimer’s disease and vascular dementia.5
Is There a Connection Between Diabetes and Alzheimer's Disease?
While there is a connection between diabetes and Alzheimer’s disease, it’s important to keep in mind that Alzheimer’s is very complex. Researchers are still learning about why some people develop the condition and others don’t. Generally, doctors and researchers believe that Alzheimer’s and dementia are caused by a combination of genetics, lifestyle, and environmental factors that impact the brain as a person ages.1 Hearing loss, concussions, poor sleep, and social isolation also contribute to the development of Alzheimer’s and dementia.5 Living with diabetes is just one of the reasons someone may have an increased risk of experiencing conditions that cause dementia.
One of the main reasons Alzheimer’s is linked to diabetes is that they both involve issues with glucose and insulin regulation in the body. Glucose is a type of sugar we get from food and drinks that the body uses for energy. The brain alone uses up to 25 percent of the glucose we consume.6 Insulin is a hormone produced in the pancreas that’s responsible for making sure the body and brain can use glucose properly. Researchers have found that changes in the way the brain uses insulin and glucose play a role in the development of Alzheimer’s disease.7-10
Studies have found that insulin not only allows the body to absorb glucose so the brain can use it for energy, it also works within the brain itself by helping neurons communicate. Neurons can become less sensitive to insulin over time, known as insulin resistance. When neurons can’t use insulin properly, they’re unable to send signals to one another effectively. This can seriously damage the neurons and contribute to the development of Alzheimer’s disease. Insulin may also help control the production of amyloid and tau proteins. Researchers think that issues with insulin in the brain lead to an overproduction of these proteins that can damage neurons.9,10
Insulin resistance can happen to those living with T2D, and individuals living with this type of diabetes may have a higher risk of experiencing Alzheimer’s because insulin resistance begins to affect their brain.9,10,14 However, insulin resistance in the brain is also present in individuals experiencing Alzheimer’s who don’t live with diabetes.15
The Relationship Between Dementia and Diabetes Complications
Experiencing diabetes complications can also affect brain health. In particular, T2D can contribute to cardiovascular complications such as heart attack and stroke, high cholesterol, and high blood pressure. Cardiovascular complications can impact blood circulation in the brain, which means that brain cells, including neurons, can’t get the nutrients and oxygen they need to function. If cardiovascular complications aren’t addressed, the brain cells can get damaged, leading to vascular dementia.14 Individuals living with T2D who experience cardiovascular complications are more likely to be diagnosed with vascular dementia than Alzheimer’s disease.14
Alzheimer’s Disease and Glucose Regulation
Because the brain relies so heavily on glucose for energy, glucose management has an impact on brain health and the development of Alzheimer’s disease. Having a high A1C is associated with an increased risk of developing dementia, even in those who do not live with diabetes. One study of adults in their 50s and older living with T1D found that those who had an A1C between 8.0% and 9.0% the majority of the time were at increased risk of being diagnosed with dementia. Those who kept their glucose levels between 6.0% and 7.9% more than half the time had a significantly lower risk of developing dementia.11
Studies also reveal that the more dramatically an individual’s glucose fluctuates—frequently experiencing highs and lows, rather than keeping glucose levels relatively stable over time—the more likely they are to develop dementia.10 Individuals who often experience hypoglycemia, or low glucose, are more likely to experience dementia.10 While those living with T1D and people living with T2D who use insulin therapy may be more likely to experience hypoglycemia, researchers don’t have enough evidence to confirm whether using insulin therapy is directly associated with an increased risk of developing dementia.10
Take Control of Your Diabetes Management to Reduce the Risk of Alzheimer’s Disease and Dementia
While there are certain things that contribute to the development of Alzheimer’s disease that are out of your control, like genetics, there are many things you can do today to support your long-term brain health and reduce your risk of experiencing dementia. Looking after your glucose levels can have a significant impact on your overall health. Those who practice consistent glucose management and meet their A1C goals are less likely to experience cognitive issues like Alzheimer’s and other conditions that can cause dementia as they age.10,11
To lower the risk of experiencing diabetes complications like dementia, Diabetes Canada generally recommends that adults living with diabetes aim for an A1C at or below 7.0% and work to keep their glucose between 3.9 and 10.0 mmol/L as often as possible.[17]12 Spending at least 70% of your time within this target range is approximately equal to a 7.0% A1C.13 For elderly people who depend on others for daily care and those who are living with dementia, Diabetes Canada generally recommends maintaining an A1C between 7.1% and 8.5%.15
Like every process in the body, glucose regulation is very complex. There are many factors that can affect your glucose levels and your A1C. It’s important to work with your doctor and diabetes care team to create a tailored plan for glucose management that works for you. Eating a balanced diet, regularly engaging in enjoyable physical activity, getting enough sleep, and managing stress are just a few ways to help control your glucose levels.
Using technology like a continuous glucose monitoring (CGM) system can give you insight into which aspects of your diabetes management routine are working well for you. With a CGM system like the Dexcom G7 CGM System, you can get real-time glucose readings on a compatible smartphone, smartwatch, or handheld receiver, without the need for routine fingersticks.*†‡ With insight into your glucose levels in the moment, you can take proactive action to stay in your target glucose range.
It’s also important to acknowledge that glucose management can be challenging, even if you’ve been living with diabetes for many years. As you age, you might notice that your body’s needs change and that you have to make adjustments to your diabetes management routines. With Dexcom G7, you can track the changes that happen in your glucose levels as time goes on and get greater insight into whether you need to talk to your doctor and diabetes care team about trying new diabetes management strategies. It’s also a good idea to attend your regular check-ups to maintain an open and ongoing conversation about your needs as they evolve over time. This gives you the opportunity to take proactive action to support your health through all the stages of your life.
Get Greater Peace of Mind Around Glucose Management with Dexcom G7
Using Dexcom CGM Systems to monitor glucose has been shown to reduce hypoglycemia, lower A1C, and increase time in range.14-24
These improvements in your glucose management can contribute to a lower risk of experiencing diabetes complications, including cardiovascular disease and conditions like Alzheimer’s that cause dementia.
In addition to giving you the convenient option to check your glucose readings in the palm of your hand, Dexcom G7 can also provide alerts about your glucose to help you take action faster. The Urgent Low Soon alert can let you know up to 20 minutes before you’re likely to experience low glucose under 3.1 mmol/L, giving you the opportunity to prevent lows before they happen. Using this alert has been shown to significantly reduce the frequency of experiencing lows.§|| You can also set up custom alerts to notify you when your glucose is higher than your target range, enabling you to take steps to get your glucose back on track as quickly as possible.
With insight into your glucose levels and proactive alerts, you’re empowered to make more informed decisions about your glucose management. This can give you a greater sense of control and provide a little extra peace of mind around knowing where your glucose is at as you continue to prioritize your health and well-being.
  • Learn more about Dexcom G7
* Smart devices sold separately. For a list of compatible devices, please visit dexcom.com/compatibility.
† Fingersticks required for diabetes treatment decisions if symptoms or expectations do not match readings.
‡ Compatible smartphone is required to pair a new Dexcom G7 sensor with a compatible Apple Watch. To use Share/Follow the smartphone must be within 10 meters (33 feet) of the Dexcom G7.
§ This predictive alert can be triggered with impending hypoglycemia (glucose of 3.1 mmol/L or below is predicted to occur within the next 20 minutes).
II Results obtained with a prior-generation Dexcom CGM system with the same Urgent Low Soon alert.
  1. Dementia numbers in Canada. Alzheimer Society. Accessed October 17, 2024. https://alzheimer.ca/en/about-dementia/what-dementia/dementia-numbers-canada
  2. Alzheimer’s Awareness Month. Statistics Canada. January 12, 2024. Accessed October 17, 2024. https://www.statcan.gc.ca/o1/en/plus/5374-alzheimers-awareness-month
  3. Alzheimer's disease. Mayo Clinic. July 10, 2024. Accessed October 17, 2024. https://www.mayoclinic.org/diseases-conditions/alzheimers-disease/symptoms-causes/syc-20350447
  4. Alzheimer's Disease. Cleveland Clinic. Reviewed October 12, 2022. Accessed October 17, 2024. https://my.clevelandclinic.org/health/diseases/9164-alzheimers-disease
  5. Dementia vs. Alzheimer’s Disease: What is the Difference? Alzheimer’s Association. Accessed October 17, 2024. https://www.alz.org/alzheimers-dementia/difference-between-dementia-and-alzheimer-s
  6. Sievert, D. Alzheimer's Vs Dementia - What Is the Difference? UCLA David Geffen School of Medicine. June 26, 2023. Accessed October 17, 2024. https://medschool.ucla.edu/news-article/alzheimers-vs-dementia-what-is-the-difference
  7. 10 ways to reduce your risk of dementia. Alzheimer Society. Accessed October 17, 2024. https://alzheimer.ca/en/about-dementia/how-can-i-reduce-risk-dementia/10-ways-reduce-your-risk-dementia
  8. Goyal MS, et al. Glucose Requirements of the Developing Human Brain. J Pediatr Gastroenterol Nutr. 2018;66 Suppl 3(Suppl 3):S46-S49. doi:10.1097/MPG.0000000000001875
  9. Kandimalla R, et al. Is Alzheimer's disease a Type 3 Diabetes? A critical appraisal. Biochim Biophys Acta Mol Basis Dis. 2017;1863(5):1078-1089. doi:10.1016/j.bbadis.2016.08.018
  10. 1Xue M, et al. Diabetes mellitus and risks of cognitive impairment and dementia: A systematic review and meta-analysis of 144 prospective studies. Ageing Res Rev. 2019;55:100944. doi:10.1016/j.arr.2019.100944
  11. Nguyen TT, et al. Type 3 Diabetes and Its Role Implications in Alzheimer's Disease. Int J Mol Sci. 2020;21(9):3165. Published 2020 Apr 30. doi:10.3390/ijms21093165
  12. Steen E, et al. Impaired insulin and insulin-like growth factor expression and signaling mechanisms in Alzheimer's disease—is this type 3 diabetes? J Alzheimers Dis. 2005;7(1):63–80. doi: 10.3233/jad-2005-7107.
  13. Rivera EJ, et al. Insulin and insulin-like growth factor expression and function deteriorate with progression of Alzheimer's disease: link to brain reductions in acetylcholine. J Alzheimers Dis. 2005;8(3):247–268. doi: 10.3233/jad-2005-8304.
  14. Cholerton B, et al. Type 2 Diabetes, Cognition, and Dementia in Older Adults: Toward a Precision Health Approach. Diabetes Spectr. 2016;29(4):210-219. doi:10.2337/ds16-0041
  15. Brubaker, P. We know about Type 1 and Type 2 diabetes, but what is ‘Type 3 diabetes’? McGill University. April 12, 2024. Accessed October 21, 2024. https://www.mcgill.ca/oss/article/medical-contributors/we-know-about-type-1-and-type-2-diabetes-what-type-3-diabetes
  16. Lacy ME, et al. Long-term Glycemic Control and Dementia Risk in Type 1 Diabetes. Diabetes Care. 2018;41(11):2339-2345. doi:10.2337/dc18-0073
  17. Imran AS, et. al. Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada: Targets for Glycemic Control. Can J Diabetes. 2018:42(S42–S46). doi: 10.1016/j.jcjd.2017.10.030
  18. What is Time in Range? JDRF Canada. Accessed October 17, 2024. https://jdrf.ca/resources/time-in-range/
  19. Beck RW, et al. JAMA. 2017;317(4):371-378.
  20. Beck RW, et al. Ann Intern Med. 2017;167(6):365-374.
  21. Martens T, et al. JAMA. 2021;325(22):2262-2272.
  22. Welsh JB, et al. J Diabetes Sci Technol. 2024;18(1):143-7.
  23. Heinemann L, et al. Lancet. 2018;391(10128):1367-1377.
  24. Puhr S, et al. Diabetes Technol Ther. 2019;21(4):155-158.

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