What did the T4DM trial show?
It showed that testosterone added to a lifestyle program lowered the rate of type 2 diabetes. T4DM enrolled 1,007 Australian men aged 50 to 74 with a waist of 95 cm (about 37.4 inches) or more, a total testosterone of 14 nmol/L (about 400 ng/dL) or lower, and either impaired glucose tolerance or newly diagnosed type 2 diabetes. Every man joined a community lifestyle program, and half also received testosterone undecanoate injections every three months for two years.
At two years, 12% of men in the testosterone group met the glucose test threshold for type 2 diabetes, compared with 21% on placebo, a relative risk of 0.59. Their two-hour glucose also improved more. The cost showed up in blood counts: hematocrit rose above 54% in 22% of men on testosterone, versus 1% on placebo, which the authors noted might limit treatment.
Why didn’t the larger TRAVERSE substudy agree?
Its result points the other way for TRT on its own. A TRAVERSE substudy followed 1,175 men aged 45 to 80 who had hypogonadism and prediabetes, using testosterone gel or placebo with no structured lifestyle program. Progression to diabetes did not differ significantly between the groups, and testosterone did not improve glucose or A1C in men with prediabetes or diabetes.
The authors concluded that TRT alone should not be used to prevent or treat diabetes in men with hypogonadism. Several differences may explain the gap: T4DM paired testosterone with a lifestyle program, used long-acting injections and measured diabetes with an oral glucose tolerance test, while TRAVERSE studied older men with heart risk using a gel. Neither trial settles which of these mattered.
Who does this apply to, and who does it not?
The evidence fits a narrow group and should not be stretched.
| Situation | What the trials suggest |
|---|---|
| Lower testosterone, large waist, prediabetes, joining a lifestyle program | T4DM supports a possible benefit, with hematocrit monitoring |
| Diagnosed hypogonadism with prediabetes, testosterone alone | TRAVERSE found no protection against diabetes |
| Normal testosterone and prediabetes | Neither trial supports testosterone for this |
| Testosterone hoped to replace diet and activity changes | Not supported; the benefit in T4DM came on top of lifestyle change |
Testosterone is approved for treating hypogonadism, not for preventing diabetes. If you have symptoms of low testosterone and prediabetes, the reason to treat is the hypogonadism, and any glucose benefit is a possible extra rather than the goal.
What lowers your diabetes risk if TRT alone does not?
Weight loss and physical activity. The NIDDK notes that in the Diabetes Prevention Program, people at high risk who lost 5% to 7% of their starting weight lowered their chance of developing diabetes. The Endocrine Society’s 2026 statement also calls weight loss the usual first-line treatment when low testosterone is tied to excess weight with no other cause.
For some men, medical weight loss with semaglutide or tirzepatide is part of that plan; see whether semaglutide can reverse prediabetes and our medical weight loss program.
How do you know if you have prediabetes?
With a blood test. The NIDDK defines prediabetes as an A1C of 5.7% to 6.4% or a fasting glucose of 100 to 125 mg/dL. Our page on the A1C test for men explains how to read your result, and our page on insulin resistance in men covers the step before it.
How Ultimate Male handles low testosterone with prediabetes
Your evaluation looks at both problems together. Labs drawn on site in San Gabriel or Downey can include A1C and fasting glucose alongside testosterone, and your provider reviews weight, waist size, sleep and medicines before discussing any hormone treatment.
If testosterone is confirmed low with symptoms, testosterone therapy may be part of the plan, with hematocrit checked at follow-up. If weight is the main driver, the plan may start with weight loss instead. Our page for men with prediabetes covers the wider picture.
