From the Guidelines
Type three diabetes refers to insulin resistance specifically in the brain, also known as Alzheimer's disease-related diabetes or brain diabetes, where impaired insulin signaling and glucose metabolism in brain cells lead to cognitive decline and potentially contribute to Alzheimer's disease progression. This condition is not officially recognized as a distinct medical diagnosis but represents a conceptual framework linking metabolic dysfunction to neurodegenerative processes. The brain becomes unable to effectively use glucose for energy, leading to cognitive decline and potentially contributing to Alzheimer's disease progression.
Key Points
- Type 3 diabetes involves impaired insulin signaling and glucose metabolism in brain cells, unlike type 1 diabetes (where the body doesn't produce insulin) or type 2 diabetes (where the body becomes resistant to insulin in peripheral tissues) 1.
- The connection between type 3 diabetes and Alzheimer's disease helps explain why people with diabetes have a higher risk of developing Alzheimer's disease, as shown in a recent meta-analysis of prospective observational studies in people with diabetes, which found a 73% increased risk of all types of dementia, 56% increased risk of Alzheimer dementia, and 127% increased risk of vascular dementia compared with individuals without diabetes 1.
- Managing blood sugar levels through diet, exercise, and possibly medications used for type 2 diabetes might help reduce the risk or slow progression of cognitive decline associated with this condition, though specific treatment protocols are still being researched.
Management Considerations
- In the presence of cognitive impairment, diabetes treatment plans should be simplified as much as possible and tailored to minimize the risk of hypoglycemia, as recommended in the 2023 standards of care in diabetes 1.
- Screening for cognitive impairment is important, especially in older adults, as discussed in Section 13 of the 2023 standards of care in diabetes 1.
From the Research
Definition of Type 3 Diabetes
- Type 3 diabetes is also known as "diabetes of the brain" or Alzheimer's disease (AD) 2, 3, 4, 5
- It is characterized by impaired glucose metabolism in the brain, similar to insulin resistance in type 2 diabetes mellitus (T2DM) 4, 5
Pathological Features
- Type 3 diabetes is associated with brain insulin resistance, which contributes to the formation of amyloid-β (Aβ) plaques and neurofibrillary tangles, two prominent pathological features of AD 3, 5
- Other shared pathological traits between type 3 diabetes and T2DM include inflammation, oxidative stress, and autophagic dysfunction 5
Therapeutic Implications
- Insulin-related therapeutic strategies may be effective in slowing down or halting the progression of AD 3, 6
- Antidiabetic medications, such as metformin, may have potential therapeutic benefits in the treatment of AD 2, 4
- Lifestyle modifications and the use of antidiabetic medications may help mitigate cognitive decline in AD patients 4