Young Men With Type 2 Diabetes Have Low Testosterone
Young Men With Type 2 Diabetes Have Low Testosterone
September 5, 2008
By Todd Neale
MedPage Today
BUFFALO, N.Y., Sept. 5 -- Young men with type 2 diabetes have low levels of testosterone, leaving them at risk for infertility, atherosclerosis, and other health problems, according to a cross-sectional study.
Among diabetic men ages 18 to 35, total testosterone concentrations were significantly lower in those with type 2 diabetes than in those with type 1 disease (11.14 versus 22.89 nmol/L, P<0.001), Paresh Dandona, M.D., Ph.D., of the State University of New York at Buffalo, and colleagues reported online in Diabetes Care.
Free testosterone concentrations were also significantly lower in men with type 2 diabetes (0.296 versus 0.489 nmol/L, P<0.001); a third of them were hypogonadal compared with 8% of the type 1 diabetics (P=0.02).
Dr. Dandona and his colleagues had previously found lower testosterone levels in middle-age men with type 2 diabetes.
"These new findings have several clinical implications besides the impairment of sexual function in these young men," Dr. Dandona said.
Low levels of testosterone may result in diminished bone mass, loss of skeletal muscle, increased weight gain and greater insulin resistance, and an elevated risk of atherosclerosis and heart disease caused by higher concentrations of C reactive protein, Dr. Dandona added.
The researchers measured serum testosterone levels in 38 men with type 1 diabetes (mean age 26.45) and 24 with type 2 disease (mean age 27.87).
The type 2 diabetics were significantly more overweight (body mass index 38.66 versus 27.41 kg/m2, P<0.001) -- 21 of 24 were obese.
The researchers compared the mean free testosterone level in the type 2 diabetics with the normal range found in a previous study of men ages 20 to 29. On the basis of that comparison, the prevalence of hypogonadism jumped from 33% to 58%.
In addition to low levels of testosterone, the type 2 diabetics had inappropriately low concentrations of luteinizing hormone and follicle stimulating hormone, according to the researchers. Patients who had low levels of all three had hypogonadotropic hypogonadism.
"Whether obesity or insulin resistance is the major determinant of hypogonadotrophic hypogonadism has to be addressed in future studies, and the pathogenesis of [the condition] needs to be defined," Dr. Dandona said.
Overall, free testosterone concentrations were negatively associated with age (P<0.01) and BMI (P<0.001).
Total testosterone levels were positively associated with luteinizing hormone (P=0.036) and follicle stimulating hormone (P<0.001) in type 1 diabetics but not in those with type 2 disease.
Free testosterone concentrations were positively associated with follicle stimulating hormone in type 1 diabetics only (P<0.01).
Levels of LH and FSH were related to each other in type 1 diabetics only (P<0.01).
Among type 2 diabetics, Hispanics had lower free testosterone concentrations than blacks (P<0.05), which was explained by the older age of the Hispanic men.
Free testosterone levels were higher in blacks than whites (P<0.05), a consequence of the lower BMI of the black men.
The researchers said that the findings have clinical importance because low testosterone levels may contribute to diminished libido and erectile dysfunction.
In addition, low levels in younger men may decrease bone mass, cause skeletal muscle to be lost, and increase weight gain, resulting in greater insulin resistance.
Infertility is a possible complication as well, they said, because below-normal levels of follicle stimulating hormone may negatively affect the development of seminiferous tubules and spermatogenesis.
"The treatment plans for such patients should include not only testosterone therapy but also the consideration of gonadotropin therapy in order to restore fertility," the researchers said.
The study was supported by a grant from the NIH to Dr. Dandona. The authors made no disclosures.
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