Men with type 2 diabetes have significantly lower testosterone levels than men without diabetes, and the relationship runs both ways: low testosterone worsens insulin resistance, while high blood sugar and excess body fat suppress testosterone production. The good news is that this suppression is largely functional, meaning it can be at least partially reversed through weight loss, better sleep, medication adjustments, and in some cases, direct testosterone therapy.
Why Diabetes Lowers Testosterone
Insulin resistance and excess body fat interfere with the hormonal signaling chain that tells your body to produce testosterone. This chain runs from the brain’s hypothalamus down to the pituitary gland and finally to the cells in the testes that manufacture the hormone. When blood sugar stays chronically elevated and visceral fat accumulates around the organs, this entire axis gets dialed down. The result is what endocrinologists call “functional hypogonadism,” a state where the testes could produce more testosterone but aren’t getting the right signals to do so.
The threshold for low testosterone is a total level below 300 ng/dL, measured on two separate mornings (testosterone peaks in the early hours and drops later in the day). The American Association of Clinical Endocrinologists recommends that all men with type 2 diabetes be evaluated for testosterone deficiency, given how common it is in this group.
Weight Loss Is the Strongest Lever
Because the hormonal suppression in most men with diabetes and obesity is functional rather than permanent, losing weight can meaningfully restore testosterone production. Fat tissue converts testosterone into estrogen and increases inflammatory signals that further suppress the brain’s hormonal commands. Reducing visceral fat reverses both of those effects.
There is no magic number for how much weight you need to lose, but even modest reductions of 5 to 10 percent of body weight improve insulin sensitivity and begin shifting the hormonal balance. The approach matters less than the result: calorie reduction, increased physical activity, or a combination both work. Resistance training deserves special mention because it stimulates testosterone production directly through muscle contraction and growth hormone release, on top of whatever fat loss it produces.
Dietary Fat Matters More Than You’d Think
A large analysis of American men’s diets and testosterone levels, published in The Journal of Urology, found that men following low-fat diets had significantly lower testosterone than men eating without fat restrictions. This held true even after controlling for age, BMI, activity level, and diabetes status. The average difference was roughly 30 ng/dL, which is clinically meaningful for someone already near the 300 ng/dL cutoff.
Your body builds testosterone from cholesterol, so chronically restricting dietary fat can limit the raw materials available. This doesn’t mean you should load up on saturated fat, which has its own cardiovascular risks that are amplified by diabetes. A balanced approach that includes healthy fats from sources like olive oil, nuts, avocados, fatty fish, and eggs gives your body what it needs without worsening metabolic health. Extremely low-fat diets are worth reconsidering if your testosterone is borderline.
Treating Sleep Apnea Can Raise Levels Substantially
Obstructive sleep apnea is extraordinarily common in men with diabetes and obesity. In one study of over 200 men hospitalized for complications of severe obesity, more than 90 percent had sleep apnea. The condition repeatedly cuts off oxygen during sleep, which directly suppresses overnight testosterone production. There’s a clear, dose-dependent relationship: the more severe the oxygen disruption, the lower the morning testosterone, independent of body weight.
Treating sleep apnea with a CPAP machine produced an average testosterone increase of about 3.75 nmol/L (roughly 108 ng/dL) after just three months. That’s a substantial jump, enough to push many men from below the deficiency threshold to above it. If you snore heavily, wake up feeling unrested despite adequate sleep hours, or your partner has noticed you stopping breathing at night, getting a sleep study could be one of the most impactful things you do for your testosterone levels.
Review Your Diabetes Medications
Metformin, the most commonly prescribed diabetes drug in the world, has a complicated relationship with testosterone in men. A randomized controlled study found that men treated with both metformin and insulin experienced a 27.4 percent reduction in testosterone levels compared to men treated with insulin alone, after just one month. This effect appeared to be independent of blood sugar control itself.
The picture isn’t entirely straightforward. In obese men with metabolic syndrome, metformin can raise levels of a protein called sex hormone-binding globulin (SHBG), which in some cases may actually trigger increased testosterone production as a compensatory response. The net effect likely depends on your starting weight, how much metabolic improvement metformin produces, and individual variation.
This is not a reason to stop metformin on your own. It remains one of the most effective diabetes medications with strong cardiovascular benefits. But if your testosterone is low and you’re on metformin, it’s worth discussing with your doctor whether the medication could be contributing and whether alternatives or additions make sense.
Newer diabetes drugs like GLP-1 receptor agonists (the class that includes semaglutide) are now being studied specifically for their effects on testosterone in men with type 2 diabetes and obesity. These medications cause significant weight loss, which should improve testosterone through the mechanisms described above. Clinical trials are currently comparing semaglutide head-to-head against testosterone replacement therapy to see which better resolves hypogonadism symptoms in this population. Early associated research has shown improvements in reproductive markers, suggesting these drugs may offer hormonal benefits beyond blood sugar control.
Testosterone Replacement Therapy
When lifestyle changes and medication adjustments aren’t enough, testosterone replacement therapy (TRT) is an option, and it has specific benefits for men with diabetes beyond just raising hormone levels. In a placebo-controlled study of men with both low testosterone and type 2 diabetes, testosterone therapy reduced fasting blood sugar by about 1.58 mmol/L, lowered HbA1c by 0.37 percent, and improved insulin resistance as measured by the HOMA index. Half of the patients who were on insulin were able to reduce their daily insulin dose by an average of 7 units while receiving testosterone.
These are meaningful metabolic improvements. The HbA1c reduction alone is comparable to what some oral diabetes medications achieve. TRT essentially addresses both sides of the cycle: it raises testosterone directly while also improving the insulin resistance that was suppressing testosterone in the first place.
TRT does carry risks. It can reduce sperm production (a concern for men who want to have children), increase red blood cell counts to potentially dangerous levels, and may worsen sleep apnea in some cases. It requires ongoing monitoring with blood tests. For men with diabetes specifically, the metabolic benefits need to be weighed against these risks in conversation with an endocrinologist or urologist experienced in managing both conditions.
Exercise and Resistance Training
Both aerobic exercise and resistance training raise testosterone levels, but they work through different routes. Aerobic exercise (walking, cycling, swimming) primarily helps by reducing body fat and improving insulin sensitivity, removing the metabolic brakes on testosterone production. Resistance training has the added benefit of triggering acute testosterone spikes during and after workouts, and building muscle mass that sustains higher baseline levels over time.
For men with diabetes, the combination is ideal. Aim for at least 150 minutes of moderate aerobic activity per week alongside two to three sessions of resistance training. Compound movements that use large muscle groups, like squats, deadlifts, rows, and presses, produce the strongest hormonal response. Overtraining, however, can backfire: excessive exercise without adequate recovery raises cortisol, which directly suppresses testosterone. Consistency matters more than intensity.
Putting It Together
The most effective approach stacks multiple interventions. Losing even a moderate amount of weight, treating sleep apnea if present, ensuring adequate dietary fat intake, exercising regularly with a resistance component, and reviewing your medication regimen with your doctor can each contribute meaningfully. For many men, these combined changes are enough to move testosterone from deficient to normal range without requiring TRT. For those who still fall short, testosterone therapy offers well-documented metabolic benefits that go beyond just symptom relief, actively improving blood sugar control and insulin sensitivity in ways that make diabetes itself easier to manage.