How is fatty liver connected to insulin resistance?
Written and medically reviewed by Zahraa Sater, M.D., M.P.H.
Reviewed August 12, 2026 · Next review due August 12, 2028
Short answer
Fat stored inside liver cells drives insulin resistance and is driven by it. The condition was renamed in 2023 from non-alcoholic fatty liver disease to metabolic dysfunction-associated steatotic liver disease, or MASLD, because it is a metabolic problem. NIDDK estimates one third to two thirds of people with type 2 diabetes have it.
Fatty liver and insulin resistance are two views of the same process. When the liver stores fat it responds poorly to insulin, so it keeps releasing glucose it should be holding back. That raises insulin demand, which promotes further fat storage. A multisociety Delphi panel renamed the condition in 2023: non-alcoholic fatty liver disease became metabolic dysfunction-associated steatotic liver disease, MASLD, and non-alcoholic steatohepatitis became MASH.
Why the name changed
The old name defined the disease by what it was not, alcohol related, and said nothing about what it is. MASLD names the mechanism, which is metabolic dysfunction: excess weight, insulin resistance, high triglycerides, low HDL, raised blood pressure and dysglycemia. The change matters clinically because it moves fatty liver out of the hepatology footnote and into the middle of metabolic care, where most of these patients are already sitting.
How common it is in diabetes
NIDDK estimates about 24 percent of US adults have fatty liver disease and that roughly one third to two thirds of people with type 2 diabetes have it. The ADA consensus report on MASLD in diabetes puts the concerning number more sharply: one in five people with type 2 diabetes has clinically significant fibrosis and is at high risk of progressing to cirrhosis. Most of them have normal or only mildly raised liver enzymes and no symptoms at all.
| Step | Test | Interpretation |
|---|---|---|
| First tier | FIB-4 score from age, AST, ALT, platelets | Below 1.3 makes advanced fibrosis unlikely |
| First tier | FIB-4 above 2.67 | Refer for specialist assessment |
| Second tier | Vibration controlled transient elastography | Below 8.0 kPa argues against advanced fibrosis |
What actually shifts liver fat
Weight loss is the treatment with the clearest dose response. NIDDK states that losing at least 3 to 5 percent of body weight can reduce fat in the liver, and that up to 7 to 10 percent may be needed to reduce liver inflammation and fibrosis. Alcohol reduction, treating sleep apnea and treating diabetes properly all help. In March 2024 the FDA approved resmetirom, the first drug for adults with noncirrhotic MASH with moderate to advanced fibrosis, to be used alongside diet and exercise.
If you have type 2 diabetes, prediabetes or central obesity, ask for a FIB-4 score. It costs nothing beyond a standard blood panel, since it is calculated from age, AST, ALT and platelet count. Normal liver enzymes do not exclude fibrosis, which is exactly why the score is calculated rather than eyeballed.
The clinical detail
Under the 2023 multisociety Delphi nomenclature, MASLD requires hepatic steatosis plus at least one cardiometabolic risk factor, which is what separates it from the older exclusion based definition. The two tier pathway endorsed in the ADA consensus report uses FIB-4 first, with values below 1.3 considered low risk, values above 2.67 prompting specialist referral, and indeterminate values moving to a second tier such as transient elastography with a threshold around 8.0 kPa.
FIB-4 performs less well in adults under 35 and over 65, where age dependent thresholds should be applied. Persistently elevated aminotransferases for more than six months with a low FIB-4 should trigger evaluation for other liver disease, including viral hepatitis, autoimmune hepatitis, hemochromatosis and drug induced injury, rather than being attributed to MASLD by default.
Written and medically reviewed by Zahraa Sater, M.D., M.P.H.
Reviewed August 12, 2026 · Next review due August 12, 2028
Sources
- A multisociety Delphi consensus statement on new fatty liver disease nomenclature. Hepatology. PMID 37364790
- Definition and Facts of NAFLD and NASH. National Institute of Diabetes and Digestive and Kidney Diseases
- Treatment of NAFLD and NASH. National Institute of Diabetes and Digestive and Kidney Diseases
- ADA consensus report calls for MASLD and liver fibrosis screening in type 2 diabetes. ACP Diabetes Monthly, American College of Physicians
- FDA Approves First Treatment for Patients with Liver Scarring Due to Fatty Liver Disease. US Food and Drug Administration
- Clinical Assessment and Management of MASLD: practice guidance. American Association for the Study of Liver Diseases
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