Age at Onset of Type 2 Diabetes Could Help Predict Risk of Dementia

An analysis of data from 10k patients in the UK suggests onset of type 2 diabetes at an earlier age could signal increased risk of dementia later in life.

This article was originally published on HCPLive.com.

Research from an international team of investigators is providing new insight into the relationship between diabetes and neurological health.

An analysis of databases from Europe, results of the study suggest earlier onset of type 2 diabetes in adulthood and midlife was linked to increased risk of developing dementia.

“In this longitudinal study, younger age at onset of diabetes was significantly associated with a higher HR of dementia. Data spanning 35 to 75 years for age of diabetes onset showed every 5-year earlier onset of diabetes was significantly associated with higher hazard of dementia,” wrote investigators. “Late-onset diabetes was not significantly associated with subsequent dementia.”

Study

The study included 7 clinical assessments between 1985 and 2016 where venous blood samples were taken either in the morning after a minimum 8-hour fast or a 5-hour fast after a light, fat-free breakfast. Fasting glucose was measured with the glucose-oxidase method.

Each examination collected data on self-reported physician-diagnosed type 2 diabetes, as well as prescriptions of diabetes medications. The national Hospital Episode Statistics (HES) database was linked for follow-up on participants.

Investigators defined type 2 diabetes as having a fasting glucose greater than 126 mg/dL at the clinical examination, use of medication, physician-diagnosed diabetes, or record of diabetes in the HES database from 1985-2019.

The team’s secondary exposures included the Finnish Diabetes Risk Score (FINDRISC), fasting glucose, and prediabetes.

Incidence of dementia was assessed using data from a trio of registers, including the HES, the Mental Health Services Data Set, and the Office for National Statistics Mortality Register, through March 2019.

Results

Within the study period, 639 patients (6.3%) were diagnosed with dementia. Investigators pointed out these patients were more likely to have chronic conditions during the follow-up period and have a worse cardiovascular risk profile at 60 years old.

When assessing incidence of diabetes, investigators found 1710 participants (16.9%) developed diabetes and 153 (8.9%) of these participants were subsequently diagnosed with dementia. Overall, dementia rates were 1.76 per 1000 person-years in participants without diabetes and 6.25 in participants with diabetes, with an HR of 1.40 (95% CI, 1.15-1.70).

At age 55, the dementia rate per 1000 person-years was 3.14 in participants without diabetes and 5.06 in participants with diabetes, at a hazard ratio (HR) of 2.14 (95% CI, 1.44-3.17). At age 70, the dementia rate was 8.85 per 1000 person-years in participants without diabetes and 13.88 per 1000 person-years in participants with diabetes, with a HR of 1.58 (95% CI, 1.22-2.03).

The data for diabetes onset from 0-5 years earlier pointed to a significant association with subsequent dementia, with an HR of 1.53 (95% CI, 1.03-2.29) and a dementia rate of 8.63 per 1000 person-years. Diabetes onset from 6-10 years earlier had a dementia rate of 10.51 per 1000 person-years.

Investigators considered diabetes status at age 70, where the HR of patients with diabetes onset more than 10 years earlier was 2.12 (95% CI, 1.50-3.00), with a dementia rate of 18.30 per 1000 person-years.

Diabetes onset 6-10 years earlier was associated with an HR of 1.49 (95% CI, 0.95-2.32), with a dementia rate of 12.99 per 1000 person-years. The rate of diabetes onset 0-5 years earlier was associated with an HR of 1.11 (95% CI, 0.70- 1.76), with a dementia rate of 10.00 per 1000 person-years.

In an analysis adjusted for sociodemographic and health factors, investigators found that at every 5-year younger age at the onset of type 2 diabetes had an association with an HR of dementia of 1.24 (95% CI, 1.06-1.46) at age 70.

Conclusion

Investigators concluded younger age at onset of diabetes had a significant association with a higher HR of dementia.

Investigators were unable to determine the specific mechanisms behind the association. They hypothesized it may be due to connections between brain metabolic dysfunction and insulin resistance, as well as higher rates of hypoglycemia in diabetes treatment increasing the risk of dementia.

The study, “Association Between Age at Diabetes Onset and Subsequent Risk of Dementia,” was published online in JAMA.