Decades after being diagnosed with type 1 diabetes, some Joslin 50-Year Medalists, who have lived 50 or more years with the disease, maintain certain types of blood cells that could help to repair blood vessels. The persistence of these endothelial progenitor cells (EPCs) and circulating progenitor cells (CPCs) may help to explain why these patients generally suffer less from cardiovascular and diabetic kidney disease than expected for those who have the disease for many years.
Reported in Diabetes Care, the results also suggest that clinical tests for CPC levels might help to identify people with type 1 diabetes who are at risk for these complications, said George King, MD, senior author on the paper, and Senior Vice President and Chief Scientific Officer at Joslin Diabetes Center.
The study examined a group of 172 Joslin Medalists with an average age of 66 years for levels of EPCs and CPCs. The results were compared to those for people of the same age without diabetes, those of the same age with type 2 diabetes and younger people with type 1 diabetes.
"We found that the Medalists in general had much higher levels of these cells than we expected, and much higher levels than other groups with diabetes," said Sonia Hernandez, PhD, co-first author on the paper.
Other studies have shown that people who have heart disease or chronic illnesses tend to have lower levels of CPCs, which also drop with age, noted King.
Among these Medalists, higher measurements of CPCs correlated with lower amounts of cardiovascular disease and kidney disease, but not reduced eye and nerve disease.
Additionally, higher measurements of EPCs were associated with lower levels of other markers of peripheral vascular disease. Previous research had shown that Medalists have experienced lower-than-expected rates of microvascular complications. Dr. King's laboratory is currently in the process of identifying factors that may be responsible for these low rates.
Following up on their findings, the Joslin team will re-examine at least half of the studied Medalists after three to five years to see whether their CPC and EPC measurements remain consistent with their cardiovascular and nerve health status. If so, measuring the levels of these cells eventually may aid in clinical tests for the risk of complications in type 1 diabetes, or in research on treatments to guard against these complications, said King, who is also a Professor of Medicine at Harvard Medical School.
More than 900 people who have had type 1 diabetes for 50 years or more have been honored as Joslin Medalists, with the first 80-Year award presented in 2013. Joslin launched a comprehensive research program in 2005 to examine why many Medalists show less severe complications, particularly eye and kidney disease, than expected for people diagnosed so long ago.
Most surprisingly so far, the Joslin program has demonstrated that most Medalists are still producing small levels of insulin, although type 1 diabetes generally had been thought to wipe out the ability to make insulin within several years of diagnosis.
"Working with the Medalists was very educational for me," commented Hernandez. "They are fantastic people, with their generosity and their willingness to not just participate in the study but to find more about the disease and teach other people."
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