Testosterone is a primary androgen hormone produced mainly in the testes of men, and in smaller amounts in the ovaries and adrenal glands of women. Diabetes mellitus is a metabolic disorder defined by high blood sugar levels resulting from the body’s inability to produce or properly use insulin. The relationship between these two conditions is complex and not a straightforward cause-and-effect scenario. Research suggests that while testosterone does not cause diabetes, maintaining healthy levels may help protect men against metabolic dysfunction. The connection primarily revolves around how testosterone influences insulin sensitivity and the management of fat and muscle tissue.
The Metabolic Role of Testosterone
Testosterone plays a significant role in carbohydrate, fat, and protein metabolism throughout the body. The hormone directly impacts insulin sensitivity, which measures how effectively cells respond to insulin to take up glucose. Higher testosterone levels in men are associated with better insulin action, allowing glucose to be utilized more efficiently by tissues.
Testosterone also influences body composition, which profoundly affects metabolic health. It promotes the maintenance and building of lean muscle mass, and muscle is a major consumer of glucose. Conversely, low testosterone is linked to increased fat mass, specifically the accumulation of visceral fat stored deep within the abdomen surrounding the organs. Visceral fat is highly metabolically active and releases inflammatory substances that impair insulin signaling, leading to insulin resistance.
The hormone acts at a molecular level, controlling the expression of certain regulatory proteins involved in processes like glycolysis and glycogen synthesis. This regulatory influence occurs in major insulin-responsive tissues, including the liver, muscle, and fat cells. By maintaining a favorable body composition and directly enhancing insulin sensitivity, testosterone supports the body’s ability to keep blood sugar levels within a healthy range.
Low Testosterone as a Diabetes Risk Factor
Observational studies consistently show that low levels of naturally occurring testosterone, known as hypogonadism, are strongly correlated with an increased risk of developing Type 2 Diabetes (T2D) and metabolic syndrome in men. Men with low testosterone are significantly more likely to have insulin resistance, a precursor to T2D. This association is so pronounced that men with T2D are estimated to be twice as likely to have low testosterone compared to men without the condition.
A complex, self-reinforcing relationship often develops, termed a “vicious cycle.” Low testosterone promotes an increase in visceral fat, and this fat tissue actively converts testosterone into estrogen via an enzyme called aromatase. Increased estrogen levels and the inflammatory state caused by obesity then suppress the signals from the brain that tell the testes to produce more testosterone, further lowering hormone levels. Insulin resistance, a hallmark of T2D, can also directly impair the function of the testosterone-producing cells in the testes, worsening the cycle.
Testosterone and Diabetes Risk in Women
The relationship is different for women with high endogenous testosterone, such as those with Polycystic Ovary Syndrome (PCOS). These women also face an increased T2D risk, but the mechanism is distinct from male hypogonadism. In PCOS, the increased T2D risk is primarily driven by hyperinsulinemia, where excessive insulin production due to insulin resistance stimulates the ovaries and adrenal glands to overproduce androgens. This high insulin level also decreases Sex Hormone-Binding Globulin (SHBG), a protein that binds testosterone, leading to higher levels of the biologically active free testosterone.
Effects of Testosterone Therapy on Glucose Control
For men diagnosed with hypogonadism and co-existing metabolic issues, Testosterone Replacement Therapy (TRT) often leads to improvements in metabolic health. Clinical studies show that restoring testosterone levels can improve insulin sensitivity, sometimes by as much as 32% in men with T2D and low testosterone. This improvement is reflected in better control of blood sugar, measured by a reduction in glycated hemoglobin (HbA1c) levels.
The metabolic benefits of TRT are closely tied to favorable changes in body composition. Treatment typically results in a significant reduction in fat mass, particularly the metabolically harmful visceral fat, and a simultaneous increase in lean muscle mass. This shift helps break the “vicious cycle” by reducing inflammatory factors and increasing the amount of glucose-consuming muscle tissue. In some long-term studies, a subset of men receiving TRT have even experienced diabetes remission.
TRT is not considered a primary treatment for diabetes itself but can be a beneficial addition to the comprehensive care plan for men with diagnosed low testosterone. Regular monitoring of HbA1c and other metabolic markers is necessary to assess the full impact of the therapy. The decision to initiate therapy requires careful consideration of the patient’s overall health profile and potential risks.