Release Date: December 7, 2006
BUFFALO, N.Y. -- Research by endocrinologists at the University at Buffalo has shown that one-third of men with type 2 diabetes who have low testosterone concentrations are likely to have anemia, due to two mechanisms that suppress the formation of red blood cells.
The anemia finding follows on the heels of UB studies showing that male diabetics who have low testosterone levels also have high levels of C-reactive protein (CRP), a marker of chronic inflammation.
"We know that testosterone stimulates the production of red blood cells, while chronic inflammation inhibits it," said Paresh Dandona, M.D., Ph.D., professor of medicine in the UB School of Medicine and Biomedical Sciences, head of the Diabetes-Endocrinology Center of Western New York and senior author on the study.
"Thus, both a low testosterone concentration and high inflammatory mechanisms may play important roles in the pathogenesis of the low-grade anemia we observed in some patients with Type 2 diabetes.
"Because high CRP concentrations are associated with atherosclerosis, and there are early data showing that low testosterone concentrations may be associated with increased cardiovascular events," said Dandona, "the anemic diabetic patient may be confronted with yet another risk factor for plaque formation in the arteries."
The study appeared in the October issue of Diabetes Care.
These results imply that physicians treating anemia in type 2 diabetic men should consider testosterone replacement, he noted, and should be aware that anemic patients may carry a very high risk of heart attack and stroke related to a high CRP.
The study involved 50 patients at the Buffalo center and 20 patients from an endocrinology specialty clinic in Midland, Texas, who had been referred to the clinics for management of type 2 diabetes. Researchers collected fasting blood samples to determine concentrations of plasma hemoglobin (the iron-containing portion of red blood cells); hematocrit (a measure of both the number and size of red blood cells); plasma testosterone; plasma CRP, certain hormones, and additional components in 16
patients who were found to be anemic.
Overall, 37 of the diabetic patients had significantly low total and free testosterone, and 30 of these men had high levels of CRP. The average hematocrit in those with low testosterone was significantly lower than in subjects with normal testosterone, and in patients with high CRP, hematocrit was lower still.
Sixteen patients were found to have anemia, but the condition was associated with iron deficiency in only one of those subjects. However, of the remaining 15 patients, 14 had low concentrations of testosterone. The concentrations of erythropoietin, a hormone that stimulates the production of red blood cells, were high in these patients, said Dandona, and thus was not a cause of this anemia.
"This demonstration of a significantly lower hematocrit in hypogonodal men and a direct relationship between hematocrit and testosterone in type 2 diabetic patients, which we are describing for the first time," said Dandona, "suggests that a low testosterone concentration may contribute to the pathogenesis of the mild anemia in these patients.
"Furthermore, the highly significant inverse relationship between CRP concentrations and the hematocrit, independent of testosterone concentrations, suggests that inflammatory processes in type 2 diabetes probably also suppress the hematocrit. It also appears that CRP, rather than being only a marker of inflammation, may contribute to inflammation by inducing adhesion of cells to vessel walls."
The authors suggest that anemia in males with type 2 diabetes should be looked for in order to identify the cardiovascular risk and that the treatment plan should involve testosterone therapy rather than erythropoietin.
Also contributing to this research, all diabetes researchers in the UB Department of Medicine, were Vishal Bhatia, M.D., Ajay Chaudhuri, M.D., Rashmi Tomar. M.D., Sandeep Dhindsa, M.D., and Husam Ghanim, M.D.
The University at Buffalo is a premier research-intensive public university, the largest and most comprehensive campus in the State University of New York. The School of Medicine and Biomedical Sciences is one of five schools that constitute UB's Academic Health Center.