Taipei, Jan. 18 (CNA) Although high blood sugar (hyperglycemia) with high glycohemoglobin, also called glycosylated hemoglobin or hemoglobin A1C (HbA1c), is known to heighten the risk of contracting diabetes, a low level of HbA1c may accelerate aging, research by Taiwan's National Health Research Institutes (NHRI) has found.
HbA1c is a hemoglobin-glucose combination formed nonenzymatically within the cell that reflects the average blood glucose level over the preceding 60-90 days. It is also widely used to monitor diabetics through common health checks and clinical examinations at hospitals.
A high level of HbA1c increases inflammation in the body, leading to the degeneration of muscle function and a lack of physical strength, said NHRI assistant investigator and attending physician Wu I-chien (吳易謙) at a press conference in Taipei Friday.
A normal HbA1c concentration level is 4.2%-5.6% of red blood cells, Wu pointed out, noting that the risk of developing diabetes increases when the HbA1c level is 5.7%-6.4%, while higher than 6.5% is defined as diabetes.
However, "one cannot say a lower HbA1c is better," Wu said, citing recent research by an NHRI team he was part of that traced the health of 2,565 initially well-functioning people aged 55 and over in Taiwan for up to five years.
In the "Healthy Aging Longitudinal Study in Taiwan" program, each participant received baseline measurements of blood HbA1c and inflammation markers levels, and their physical health was repeatedly assessed over a mean follow-up period of 5.3 years.
The team found that compared to participants with an HbA1c of 5.5%-6.0%, those with an HbA1c of under 5.5% or above 7.0% experienced a higher annual increase in the likelihood of physical impairment, according to the research results, which were published in June 2018 in the Journals of Gerontology: Medical Sciences.
The journal is the main academic publication by the Gerontological Society of America.
When the HbA1c level was lower than 5.5%, even if it remained within the normal level, the risk of physical impairment was found to increase by a factor of 1.25 times each year, Wu said.
The study concluded that "high and low HbA1c levels at baseline are associated with faster physical functioning decline, particularly among individuals with elevated circulating soluble interleukin-6 receptor, a sign of enhanced interleukin-6 trans-signaling," according to the published research results.
Interleukin-6 (IL-6) is a cytokine that plays an important role in many chronic inflammatory diseases.
Wu said a high or low level of HbA1c with an increase of certain inflammation-induced substances could be a sign of early aging.
At Friday's press event, Hsu Chih-cheng (許志成), deputy director of the NHRI's Institute of Population Health Sciences, advised people over 40 to have regular health checks as a preemptive measure to prevent early aging.