Living in a retirement community, I see many people develop and progress to severe Alzheimer’s disease. This is the disease that most of us fear the most, as it robs us of our “self.” I previously wrote about steps to reduce your risk. One was to avoid diabetes, as it substantially increases the risk of dementia. Of course, avoiding diabetes is reason enough, as it is a potentially severe disease with many downstream complications to the heart, eyes, brain, kidneys, and nerves. But here, I would like to review how you can determine whether you are at risk for diabetes and how to mitigate it, thereby substantially reducing your risk of later Alzheimer’s disease.
Diabetes
40 million Americans have diabetes mellitus, or 12% of the population. Of these 38 million have type 2 diabetes (previously known as “adult onset”) and 2 million have type 1 (previously known as “juvenile diabetes.) 29 million have been diagnosed, yet 11 million are unaware that they have the disease. Our focus is type 2 diabetes.
Diabetes type 2 incidence increases with age, such that nearly 30% of those over 65 have diabetes, compared to ages of 40 to 59 with a 12% incidence, and 4% for those under 40.
Of great concern is the rising incidence over time. In 2000, a total of 8% of Americans had diabetes. This has risen to about 12% or a 50% increase in just two decades. Some would term this an epidemic. Of further concern, many young people are now developing diabetes.
Diabetes substantially increases the risk of multiple diseases. Among them are blindness, kidney failure (the most common reason for a kidney transplant is diabetes damage), cardiovascular disease, including heart attacks and strokes, loss of sensation in the feet and lower legs (neuropathy and paresthesia), reduced vascular supply to the lower legs and the feet, often resulting in amputation of toes, feet, or legs, and Alzheimer’s disease.
Diabetes and its associated diseases combined cost America $640 billion per year, or 25% of all healthcare spending.
The major risk factors for type two diabetes include being substantially overweight, having a family history, being inactive or sedentary, and being over the age of 45.
You can’t change your family history. But your genes need not be your destiny. The basics of prevention include losing weight, increasing activity, eating healthy foods, and substantially reducing the intake of ultra-processed foods.
Diabetes and Alzheimer’s disease
Type 2 diabetes increases the risk of Alzheimer’s disease by 50 to 65%. It’s a shared risk factor with increased blood pressure and increased cholesterol, all leading to brain cell inflammation.
The increased risk of diabetes correlates with insulin resistance not only throughout the body but also in the brain. Some scientists think that brain insulin resistance is separate from the resistance in other parts of the body, and as a result, use the term “type 3 diabetes” as a synonym for Alzheimer’s disease. The brain cells are in effect “starved” for glucose, which is the neurons’ principal source of energy, despite plenty of glucose circulating in the bloodstream.
Insulin resistance of brain cells is associated with increased oxidative stress and neuroinflammation, which in turn leads to neurodegeneration.
Bottom line — reducing the possibility of developing diabetes markedly reduces your chances of developing Alzheimer’s disease. Diabetes begins with prediabetes, so the place to start your preventive work is there.
Prediabetes
115 million Americans have prediabetes. 81% do not know it. 18% of teens have prediabetes, and this number is on the rise.
The typical person with prediabetes is overweight, has excess belly fat, and is sedentary. They tend to eat a diet high in sugar and foods that are quickly digested into sugar, as well as ultra-processed foods. Many will also have a family history of diabetes.
Those with prediabetes have a 5–10% chance of progressing to diabetes each year, which accumulates so that in 3–5 years, 15–30% will have developed diabetes. And, if followed for enough years, up to 70% will progress.
Prediabetes is diagnosed by measuring your average blood glucose over the course of 2 to 3 months. This is done with a test called A1c, a blood test that can be drawn at any time of day. If the A1c is between 5.7% and 6.4%, that is diagnostic of prediabetes. If it’s 6.5% or higher, that’s diagnostic of diabetes. As noted, most people with prediabetes don’t know it. However, the A1c test is simple and inexpensive. If you have any of the risk factors for prediabetes, it’s well worth your while to have the test. Your doctor may order it at your annual evaluation. Ask to have it done and then ask for the result.
Knowing you have prediabetes is essential because the progression to diabetes can be reversed with lifestyle changes. Yes, these can be challenging, but they are well worth the time and effort so that you do not progress to diabetes and all of its downstream complications, including dementia.
The other reason to reverse prediabetes is that it is not a benign condition. It is silent but causes trouble over time. Prediabetes leads to slow but long-term damage to blood vessels, the heart, and the kidneys. Prediabetes can be part of the metabolic syndrome — a combination of any three of elevated blood sugar, high blood pressure, high LDL cholesterol and low HDL cholesterol, elevated triglycerides, and excess belly fat. These conditions in combination lead to diabetes, heart disease, stroke, fatty liver disease, and cognitive decline.
Although usually not measured, the underlying problem is the early stages of insulin resistance when the pancreas can still compensate by producing excessive insulin to overcome the resistance. Once it can no longer do that, blood glucose remains high, and you now have diabetes.
Reversing prediabetes
The good news is that you can reverse prediabetes back to normal. The steps are straightforward and usually do not require medication. Since prediabetes develops because of being overweight, being sedentary, and eating too much sugar and foods that readily convert to sugar, the steps are straightforward.
Check your waist-to-height ratio. Your waist should be less than 50% of your height. Details here.
Losing just 5 to 7% of body weight will reduce the risk of progressing to diabetes by 50%. For a 200-pound person, this is only 10–14 pounds. The second step is to get about 150 minutes of aerobic exercise each week. A brisk 30-minute walk five days a week will suffice. Add resistance exercises 2 to 3 times per week.
The third step is to eat a low-glycemic (meaning food that does not digest to sugar rapidly and thereby leads to rapid increases in blood sugar — think candy, ice cream, cakes), micronutrient-dense diet that includes increased fiber intake, non-starchy vegetables (for example, dark green veggies), whole grains (whole wheat, brown rice), legumes (beans and lentils), lean meats, fish, eggs, nuts, and avocados.
It is very important to reduce sugary drinks and high-sugar foods, such as pastries, pies, and ice cream. Eating only whole grains means no products made from white flour, such as white bread, most prepared cereals, pastries, and donuts.
Avoid ultra-processed foods, as they contain high levels of sugar, salt, and white flour. Ultra-processed foods themselves are linked to dementia. It is also important to get adequate sleep and to reduce chronic stress.
It’s a good idea to monitor your progress with continuous glucose monitoring. It will show you whether certain foods cause spikes in blood sugar and how exercise affects it. These monitors are now available at most pharmacies.
These lifestyle changes can reverse prediabetes within a few months.
You want to get your A1c level down, not just to the upper limit of normal at 5.6, but lower still, because the cutoff from normal to prediabetes, although highly useful, is still a static number. You want to be well under the top limit of “normal.”
Some people have tried but cannot lose weight or can’t keep it down after losing. They often benefit from using a GLP1 drug such as Wegovy (semaglutide) and Zepbound (tirzepatide). For many people, these have proven highly valuable. A word of caution. Weight loss usually includes both fat and muscle, so you need to do resistance exercises to counteract muscle loss. Once started, many people need to continue indefinitely, otherwise they regain weight, fat, but not muscle.
It is to your definite advantage to learn if you have prediabetes and then to do what is needed to reverse it. Habits can be difficult to modify, but the benefits are so great that the time and effort are well worth it, including a major risk reduction in dementia. And remember, it is never too late to get started.
With thanks to retired long-time expert diabetes educator Charlene Freeman, RN CDE CPT
