Blood sugar & insulin
After you eat, glucose enters your blood, and the pancreas releases insulin to move it into your muscles, liver, and fat cells. Muscle is the biggest destination, which is one reason strength training matters so much for blood sugar.
In insulin resistance, those tissues respond less and less, so the pancreas pumps out more insulin to compensate. For years, sometimes a decade or more, that extra insulin keeps blood sugar looking normal on tests. Eventually the pancreas can't keep up, glucose starts to rise into the prediabetes range, and then into type 2 diabetes.
That long silent phase is the opportunity. Insulin resistance is very reversible, especially early.
Prediabetes & diabetes numbers
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| A1c (3-month average) | Under 5.7% | 5.7–6.4% | 6.5%+ |
| Fasting glucose | Under 100 | 100–125 | 126+ |
| 2-hour glucose tolerance test | Under 140 | 140–199 | 200+ |
Glucose values in mg/dL. A diabetes diagnosis generally needs two abnormal results. The American Diabetes Association recommends screening all adults from age 35, and earlier if you're overweight with other risk factors.
A fasting insulin test can reveal insulin resistance before glucose rises, but it isn't standardized across labs. Your triglycerides-to-HDL ratio, waist size, and blood pressure are often just as telling.
Belly fat & insulin resistance
Where you carry fat matters as much as how much. Visceral fat, stored deep in the abdomen around the organs, is far more metabolically harmful than fat under the skin. It releases inflammatory signals and fatty acids that drive insulin resistance, fatty liver, and high triglycerides.
Men tend to store fat viscerally, which is part of why they develop metabolic disease earlier. Your waist measurement is a better quick guide than BMI:
- Over 40 inches (102 cm) is a standard threshold for elevated risk in men.
- A lower threshold, around 35–37 inches, is often used for men of South or East Asian descent, who develop metabolic disease at lower body weights.
- Another simple guide is keeping your waist under half your height.
Muscular men can have a "high" BMI with healthy metabolism, and "skinny fat" men with a normal BMI can have plenty of visceral fat. That's why waist and labs beat the scale.
Metabolic syndrome
Metabolic syndrome is a cluster of risk factors that together substantially raise the risk of type 2 diabetes and heart disease. It's diagnosed when a man has three or more of these five:
| Criterion | Threshold (men) |
|---|---|
| Waist circumference | Over 40 in (102 cm) |
| Triglycerides | 150 mg/dL or higher, or on treatment |
| HDL cholesterol | Under 40 mg/dL, or on treatment |
| Blood pressure | 130/85 or higher, or on treatment |
| Fasting glucose | 100 mg/dL or higher, or on treatment |
It's very common, affecting roughly a third of U.S. adults, and rising with age. Our number checker will tell you how many criteria you meet.
The testosterone connection
Low testosterone and metabolic problems feed each other:
- Excess visceral fat lowers testosterone. Fat tissue converts testosterone to estrogen, and obesity-related inflammation and insulin resistance suppress the brain's signal to the testes.
- Low testosterone makes it easier to gain fat and lose muscle, which worsens insulin resistance.
- As a result, low testosterone is common in men with type 2 diabetes and metabolic syndrome, often in a third or more.
The good news is that the loop runs in reverse, too. Meaningful weight loss, whether from lifestyle, medication, or bariatric surgery, often raises testosterone substantially on its own. For men with genuinely low levels, TRT improves body composition and can modestly improve insulin sensitivity, but it works best alongside, not instead of, fixing the metabolic side.
Fatty liver
Fat buildup in the liver linked to metabolic health, now called MASLD (metabolic dysfunction-associated steatotic liver disease, formerly NAFLD), affects roughly a third of adults. It's usually silent and is often first noticed as a mildly raised ALT on routine bloodwork, or on an ultrasound done for something else.
Most cases don't progress, but some develop into inflammation and scarring (fibrosis), which can eventually lead to cirrhosis. If you have metabolic syndrome or type 2 diabetes, ask your doctor about a fibrosis risk check, such as a FIB-4 score from routine labs or a liver elastography scan. Weight loss of around 7–10% is the most effective treatment, and cutting alcohol matters.
What reverses it
The landmark Diabetes Prevention Program trial found that modest weight loss (about 7% of body weight) plus 150 minutes a week of activity cut the risk of progressing from prediabetes to diabetes by 58%, significantly better than the drug metformin. The effects were still visible years later.
- Lose 5–10% of your body weight if you're carrying extra. Even this modest amount improves insulin sensitivity, blood sugar, triglycerides, blood pressure, and fatty liver.
- Lift weights. More muscle means more places to store glucose, and each session improves insulin sensitivity for a day or two. Starter programs →
- Walk after meals. Even 10–15 minutes of walking after eating noticeably blunts the blood sugar rise.
- Get your aerobic minutes. 150+ minutes a week of moderate activity.
- Eat mostly minimally processed food. Prioritize protein, vegetables, legumes, whole grains, and healthy fats. Cut sugary drinks, which are the easiest win. Several eating patterns work (Mediterranean, lower-carb, plant-forward). The best one is the one you can sustain.
- Sleep 7+ hours and treat sleep apnea. Even a few nights of short sleep measurably worsen insulin sensitivity.
- Limit alcohol, which drives triglycerides, fatty liver, and belly fat.
GLP-1 medications
GLP-1-based medications, including semaglutide (Ozempic for diabetes, Wegovy for weight) and tirzepatide (Mounjaro for diabetes, Zepbound for weight), have changed obesity treatment. They reduce appetite, slow stomach emptying, and improve blood sugar control.
- ✓Weight loss: average losses of roughly 15% of body weight with semaglutide and around 20% with high-dose tirzepatide in major trials. That's far more than older drugs.
- ✓Heart benefits: in a large trial of people with heart disease and overweight but no diabetes, semaglutide reduced major cardiac events by about 20%.
- ✓Other benefits: improvements in blood pressure, fatty liver, and sleep apnea. Tirzepatide is FDA-approved for moderate-to-severe sleep apnea in adults with obesity.
The trade-offs
- ✕Muscle loss. A substantial share of the weight lost can be lean mass, not fat. Strength training and enough protein are essential while on these drugs. Protein calculator →
- ✕Side effects: nausea, constipation, diarrhea, and reflux are common, especially when increasing the dose. Gallbladder problems and pancreatitis are less common but serious.
- ✕Weight tends to return after stopping, so they're generally treated as long-term medications.
- ✕Cost and coverage vary widely. Insurance coverage for weight loss (vs. diabetes) is inconsistent.
Many telehealth men's health clinics now prescribe GLP-1s alongside TRT. If you're considering one, the same rules apply as with TRT: proper baseline labs, a real medical evaluation, and ongoing follow-up. Compare providers →
Metformin & other options
- Metformin is inexpensive, has decades of safety data, and is sometimes used for prediabetes, particularly in younger people with a higher BMI. It typically causes little or no weight loss. It's also promoted as a "longevity drug," but that hasn't been proven in healthy people. Some research suggests it may blunt some of the gains from exercise.
- SGLT2 inhibitors (empagliflozin, dapagliflozin) are diabetes drugs with proven heart and kidney benefits, often prescribed for people with type 2 diabetes plus heart or kidney disease.
- Bariatric surgery remains the most effective long-term treatment for severe obesity and often puts type 2 diabetes into remission.
Should you wear a glucose monitor?
Continuous glucose monitors (CGMs), small sensors worn on the arm, are now sold over the counter. For people with diabetes, they're a genuinely valuable tool.
For people without diabetes, the picture is more mixed. A few weeks of wear can be an eye-opening way to see how specific meals, sleep, alcohol, and walks affect you. But healthy people's glucose normally rises after meals, and there's no good evidence that chasing a perfectly flat line improves health. If a CGM makes you anxious about eating normal foods like fruit, it's doing more harm than good. An A1c, fasting glucose, and waist measurement tell you most of what you need to know.