Educational

Fatty liver disease shows up in a majority of people with type 2 diabetes — estimates commonly land between 55% and 70%, depending on the population and how it's measured.

It's usually described as a consequence, something that happens downstream of insulin resistance. That's half the picture. The liver, once it accumulates fat, actively drives blood sugar higher, which drives more fat into the liver.

The name changed, and it matters

What was non-alcoholic fatty liver disease (NAFLD) was renamed in 2023 to metabolic dysfunction-associated steatotic liver disease — MASLD.

The old name defined the condition by what it wasn't. The new one names what it is: a liver condition arising from metabolic dysfunction, which sits it alongside type 2 diabetes rather than in a separate category. Diagnosis now requires at least one cardiometabolic risk factor, so the link is built into the definition.

How the loop works

Insulin's job in the liver is to tell it to stop producing glucose. When the liver becomes insulin resistant, that instruction stops landing, and the liver keeps releasing glucose regardless of how much is already circulating.

That's the main reason fasting glucose runs high. You haven't eaten for ten hours and your liver has spent those hours pouring glucose into the bloodstream because the signal to stop isn't getting through.

Fat accumulating inside liver cells is a major contributor to that resistance. And the resulting high insulin levels tell the liver to produce more fat, through a process called de novo lipogenesis. Each side worsens the other.

Fructose has a specific role here

Glucose gets used all over the body. Fructose is metabolised almost entirely in the liver, and when it arrives faster than the liver can use it, a substantial share gets converted to fat on site.

The dose is what matters. Fructose from whole fruit arrives slowly, packaged with fibre and water, in amounts the liver handles easily. Fructose from sugar-sweetened drinks arrives in a bolus with nothing to slow it.

That's why sugar-sweetened beverages come up repeatedly in the MASLD literature as an independent risk factor, and why they're usually the first thing to address. High-fructose corn syrup and table sugar behave similarly here — sucrose is half fructose, so the distinction matters less than the total.

What the evidence says works

Weight loss, with thresholds. The literature is unusually specific: around 5% of body weight tends to reduce liver fat, 7% or more improves the inflammatory component, and 10% or more is where fibrosis improvement becomes likely. Those are meaningful thresholds rather than a smooth gradient.

Reducing refined carbohydrate and sugar. Studies restricting carbohydrate — particularly sugars — show reductions in liver fat that occur faster than weight loss alone explains. This is where glycemic load connects directly: a lower-GL pattern reduces both the insulin signal driving fat production and the fructose load arriving at the liver.

Exercise, independent of weight. Both aerobic and resistance training reduce liver fat even when body weight doesn't change. That's an unusually clean finding and a useful one for anyone whose weight has stalled.

A Mediterranean pattern. It has the most trial support of any named dietary pattern for this condition — olive oil, fish, vegetables, legumes, nuts, limited refined carbohydrate.

Coffee. Consistently associated with lower liver fat and less fibrosis across large observational studies. The association is strong enough and consistent enough to mention, while remaining observational.

Finding out whether you have it

MASLD is usually silent. It's often picked up incidentally on an ultrasound, or suspected from mildly raised liver enzymes on a routine blood panel.

Normal enzymes don't rule it out, which catches people out. A common next step is a FIB-4 score, calculated from age, platelet count and two enzyme values you probably already have, which estimates the likelihood of significant fibrosis. Elastography — a scan measuring liver stiffness — is the usual follow-up.

If you have type 2 diabetes and have never been assessed for this, it's a reasonable thing to raise. Several diabetes guidelines now recommend routine screening in exactly that group.

What about alcohol, given the old name

The old label — non-alcoholic fatty liver disease — created a fair amount of confusion, since alcohol also causes fatty liver by a different route, and the two can coexist.

The current framework acknowledges that overlap explicitly, with a category for people who have both metabolic risk factors and meaningful alcohol intake. For anyone with metabolic fatty liver, alcohol adds a second insult to the same organ, and reducing it is one of the more direct things available.

There's no threshold I can give you that applies generally. What's reasonable depends on how much liver damage is already present, which is a question for whoever's assessing it.

Why it's worth taking seriously

Most people with MASLD never develop advanced liver disease. A minority progress to fibrosis, cirrhosis, and liver failure, and MASLD is now among the leading reasons for liver transplantation.

The more common outcome is cardiovascular: people with MASLD are more likely to die of heart disease than of anything to do with the liver. It travels with the same cluster — high triglycerides, low HDL, hypertension, insulin resistance.

The encouraging part is that early MASLD is genuinely reversible. Liver fat responds quickly to changes in diet and activity — often within weeks, and faster than most other markers move. It's one of the more responsive things in this whole field, which makes it worth knowing about rather than worth worrying about.