ATLANTA – Men with type 1 diabetes might not express an elevated level of prostate specific antigen, even if they have an early prostate cancer, suggest findings from a subanalysis of patients with type 1 diabetes.
In that prospective study, poor glycemic control was associated with decreased PSA levels, irrespective of age or body size, Dr. James Hotaling said during a poster session at the annual meeting of the American Urological Association.
"It’s well known that patients with type 2 diabetes have a decreased risk of prostate cancers as well as lower PSAs," said Dr. Hotaling of the University of Washington, Seattle.
"This lower PSA is thought to stem from a greater volume of distribution because many of these men are overweight or morbidly obese – and some hypothesize that they have lower testosterone because of the obesity and that this contributes to these findings."
Dr. Hotaling and his colleagues sought to determine whether men with type 1 diabetes showed a similar pattern. To do this, they examined data from year 17 of the Epidemiology of Diabetes Interventions and Complications (EDIC) study. EDIC began in 1994 and is the observational follow-up study of 1,441 participants in the earlier Diabetes Control and Complications Trial (DCCT).
PSA concentrations were measured in 627 men during year 17. The investigators stratified the subjects by both age (younger than 40 years, 41-59 years, and 60 years and older) and body mass index (normal, overweight, obese).
The subjects were a mean age of 52 years at the time of PSA measurement. Their mean HbA1c was 8%, and the mean PSA 0.93 ng/mL.
PSA levels increased with age, from a low of 0.56 ng/mL in the youngest patients to a mean of 1.38 ng/mL in the oldest group.
PSA levels significantly decreased as HbA1c increased. The mean PSA was 1.05 ng/mL when blood sugar was less than 7.5% and 0.76 ng/mL when blood sugar was above 8.5%.
"Each 10% increase in HbA1c levels was associated with a PSA reduction of 1.37ng/mL," Dr. Hotaling said. "This association was independent of age and body size."
Our findings suggest that metabolic differences related to diabetes may affect the ability to detect early-stage prostate cancer. This finding also could represent a potentially modifiable risk factor that could be addressed.
The physiologic relationship between hyperglycemia and low PSA is not completely known, he added. "Proposed mechanisms are that hyperinsulinemia and insulin resistance lead to increased estradiol, which causes decreased testosterone and sex hormone–binding globulin, thus leading to a decreased PSA concentration."
EDIC is sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases. Dr. Hotaling reported having no financial disclosures.