A new study indicates that high levels of the hormone testosterone are linked with a raised risk of diabetes and prostate enlargement.
University of California researchers conducted saliva tests on 350 adult males in the Tsimane tribe, an isolated population in the Bolivian rainforest.
Advanced cases of prostate enlargement were found to be virtually non-existent, with the Tsimane also observed to have low testosterone levels and low levels of glucose in the blood – indicating a reduced risk of developing diabetes.
While, on the whole, the Tsimane had low testosterone, those with higher levels were found to have larger prostates. The researchers also examined the HbA1c levels of the participants, and found those with larger prostates also had higher HbA1c readings.
Type 2 diabetes is caused by overly high glucose levels on the blood, with Professor Michael Gurve, UC, reporting: “Type 2 (adult onset) diabetes is one of these illnesses that under more traditional conditions wouldn’t be as prevalent as it is today in high-income countries, or becoming increasingly prevalent in urban areas of low-income countries. As groups of the Tsimane undergo change, we might very well see an increase in diabetes.”
Dr Benjamin Trumble added: “Among men with low testosterone and low diabetes risk, those with relatively higher testosterone or HbA1c were at higher risk of prostate enlargement.”
Nine in ten Tsimane men experienced prostate enlargement, clinically known as benign prostatic hyperplasia (BPH), with researchers highlighting that this places doubt over the millions of men who use supplements for low testosterone levels.
The researchers suggest that more long-term studies are necessary to assess the safety and efficacy of testosterone-replacement therapy in men.

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