Alzheimer’s disease, the most common form of dementia, is increasingly being referred to in medical circles as “type 3 diabetes.” Insulin is not just a regulator of blood sugar; it plays a vital role in the brain’s memory and learning centers. When diabetes causes insulin resistance to rise, it can impair these cognitive functions. According to a 2024 report by the Lancet Commission, individuals with diabetes face a 1.7-fold higher risk of developing dementia.
As diabetes is identified as a primary risk factor, a new study suggests that for women with type 2 diabetes, a longer reproductive period may serve as a protective buffer against cognitive decline.
Big Data Reveals the Estrogen Connection
A research team led by Professor Seung-hwan Lee of Seoul St. Mary’s Hospital, in collaboration with Professor Kyung-do Han’s team at Soongsil University, analyzed National Health Insurance Service big data. They followed 159,751 postmenopausal women with type 2 diabetes for an average of 8.3 years. During this period, 24,218 cases of dementia were recorded, including 18,819 cases of Alzheimer’s and 2,743 cases of vascular dementia.
The study, published in the American Diabetes Association’s journal Diabetes Care, found a clear correlation: the earlier the age at menarche and the later the age at menopause, the lower the risk of dementia.
Reproductive Span: Women with a reproductive period (the interval from menarche to menopause) of 40 years or longer had a 27% lower risk of dementia compared to those with a span of less than 30 years.
Hormone Therapy: Those who received hormone replacement therapy (HRT) for five years or longer showed a 17% lower risk than those who did not.
The Role of Lifetime Hormone Exposure
The research team suggests that for women with diabetes, cognitive health is influenced not only by blood glucose management but also by lifetime exposure to female hormones like estrogen.
“We have confirmed that factors such as reproductive span, childbirth history, breastfeeding history, and hormone therapy are potentially linked to long-term brain health,” the team explained. Estrogen is believed to have neuroprotective effects, which may help mitigate the neurological damage often exacerbated by diabetic insulin resistance.
Professor Seung-hwan Lee emphasized the need for continued exploration: “Further studies incorporating specific hormone levels, diabetes severity, and neuroimaging data are required to clarify these biological mechanisms more precisely.” For now, the findings highlight a significant intersection between endocrine history and neurological resilience in diabetic patients.
