Can prediabetes cause fatty liver? This question reflects growing awareness of the strong link between non-diabetic hyperglycaemia (prediabetes) and non-alcoholic fatty liver disease (NAFLD). Whilst prediabetes does not directly cause fatty liver in a simple cause-and-effect manner, the two conditions are closely interconnected through shared metabolic disturbances, particularly insulin resistance. Research shows that individuals with prediabetes face an elevated risk of developing NAFLD, with estimates suggesting one-third to one-half of those with prediabetes also have some degree of fatty liver disease. Understanding this relationship is crucial, as early lifestyle intervention can significantly improve both conditions and reduce the risk of progression to type 2 diabetes and advanced liver disease.

Understanding Prediabetes and Fatty Liver Disease

Non-diabetic hyperglycaemia (NDH), often referred to as prediabetes, is a metabolic condition characterised by blood glucose levels that are higher than normal but not yet high enough to meet the diagnostic criteria for type 2 diabetes mellitus. In the UK, the NHS Diabetes Prevention Programme (NHS DPP) defines NDH as an HbA1c level of 42–47 mmol/mol (6.0–6.4%) or a fasting plasma glucose of 5.5–6.9 mmol/L. (Note: the World Health Organization uses 6.1–6.9 mmol/L for impaired fasting glucose; UK services typically use the broader 5.5–6.9 mmol/L threshold for programme eligibility.) This intermediate state affects millions of people in the UK and represents a critical window for intervention to prevent progression to type 2 diabetes.

Non-alcoholic fatty liver disease (NAFLD) is the accumulation of excess fat in the liver (hepatic steatosis) in individuals who consume little to no alcohol (defined as ≤14 units per week in line with UK Chief Medical Officers' guidance). It exists on a spectrum from simple steatosis to non-alcoholic steatohepatitis (NASH), which involves inflammation and liver cell damage, and can progress to fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD is now recognised as the most common chronic liver condition in the UK, affecting a substantial proportion of adults to varying degrees. (Note: international consensus is moving towards the term metabolic dysfunction-associated steatotic liver disease (MASLD); however, NHS resources and NICE guidance currently use NAFLD.)

Both conditions share common underlying metabolic disturbances and are strongly associated with obesity, sedentary lifestyle, and poor dietary habits. The relationship between NDH and fatty liver disease is bidirectional and complex, with each condition potentially influencing the development and progression of the other. Understanding this connection is essential for healthcare professionals and patients alike, as early recognition and lifestyle modification can significantly alter the trajectory of both conditions and reduce the risk of serious complications including cardiovascular disease, type 2 diabetes, and advanced liver disease.

Can Prediabetes Cause Fatty Liver?

The relationship between non-diabetic hyperglycaemia (prediabetes) and fatty liver disease is well-established in medical literature, though it is more accurate to describe them as closely interconnected conditions sharing common metabolic roots rather than one directly causing the other. Research consistently demonstrates that individuals with prediabetes have an elevated risk of developing NAFLD compared to those with normal glucose metabolism. Estimates vary by population, diagnostic methods, and body mass index, but studies commonly report that a substantial proportion—often around one-third to one-half—of people with prediabetes also have some degree of fatty liver disease.

Rather than a simple cause-and-effect relationship, prediabetes and NAFLD share common underlying pathophysiological mechanisms, particularly insulin resistance and metabolic dysfunction. These shared metabolic disturbances mean that the conditions often develop in parallel, each potentially accelerating the progression of the other. The presence of prediabetes indicates that metabolic dysfunction has reached a level where glucose regulation is impaired, and this same dysfunction promotes fat accumulation in the liver.

It is important to note that whilst prediabetes is strongly associated with fatty liver disease, not everyone with prediabetes will develop NAFLD, and conversely, fatty liver can occur in individuals without prediabetes. Other risk factors play important roles, including:

• Central obesity (excess abdominal fat)

• Dyslipidaemia (abnormal cholesterol and triglyceride levels)

• Hypertension

• Genetic predisposition

• Dietary factors, particularly high intake of refined carbohydrates and fructose

• Obstructive sleep apnoea

The co-occurrence of these conditions is common. However, NICE does not recommend routine screening for NAFLD in primary care populations, including those with prediabetes. If NAFLD is suspected—for example, due to abnormal liver blood tests or incidental steatosis on imaging—healthcare professionals should assess fibrosis risk and manage accordingly, as outlined in NICE guideline NG49.

How Insulin Resistance Links Prediabetes and Fatty Liver

Insulin resistance is the fundamental metabolic abnormality that connects prediabetes and fatty liver disease. In this state, cells throughout the body—particularly in muscle, fat tissue, and the liver—become less responsive to insulin's signals. The pancreas compensates by producing more insulin (hyperinsulinaemia), but eventually this compensatory mechanism becomes insufficient, leading to elevated blood glucose levels characteristic of prediabetes.

In the liver, insulin resistance disrupts normal metabolic processes in several critical ways. Insulin normally suppresses hepatic glucose production and promotes glucose storage as glycogen. When insulin resistance develops, the liver continues producing glucose inappropriately (via gluconeogenesis and glycogenolysis), contributing to hyperglycaemia. Simultaneously, hyperinsulinaemia continues to activate sterol regulatory element-binding protein-1c (SREBP-1c), a transcription factor that upregulates genes involved in de novo lipogenesis—the synthesis of new fatty acids from excess carbohydrates. Although the liver may increase secretion of very-low-density lipoproteins (VLDL) to export triglycerides, this compensatory mechanism is often insufficient to offset the excess triglyceride synthesis and influx from other sources, resulting in progressive fat accumulation within hepatocytes.

Additionally, insulin resistance in adipose tissue leads to increased lipolysis, releasing free fatty acids into the circulation. These fatty acids are taken up by the liver, providing another major source of hepatic fat accumulation alongside de novo lipogenesis and dietary fat intake.

The accumulated fat within the liver can trigger inflammatory pathways and oxidative stress, potentially progressing from simple steatosis to NASH. This inflammatory state further worsens insulin resistance, creating a vicious cycle. The liver's central role in glucose metabolism means that hepatic insulin resistance significantly contributes to the deterioration of glycaemic control, accelerating progression from prediabetes to type 2 diabetes. This interconnected pathophysiology explains why addressing insulin resistance through lifestyle modification benefits both conditions simultaneously.

Symptoms and Diagnosis of Fatty Liver in Prediabetes

NAFLD is typically asymptomatic in its early stages, which presents a significant challenge for early detection. Most individuals with fatty liver disease, including those with concurrent prediabetes, experience no noticeable symptoms until the condition has progressed significantly. When symptoms do occur, they are often non-specific and may include:

• Persistent fatigue and general malaise

• Vague discomfort or fullness in the right upper abdomen

• Unexplained weakness

More advanced liver disease may present with jaundice, ascites (fluid accumulation in the abdomen), peripheral oedema, or signs of hepatic encephalopathy, though these indicate significant liver damage and are uncommon in the prediabetic population.

Diagnosis of NAFLD often occurs incidentally during investigations for other conditions. NICE does not recommend routine screening for NAFLD in primary care populations. However, if NAFLD is suspected—for example, due to abnormal liver function tests (LFTs) or incidental steatosis detected on imaging—appropriate assessment should be undertaken. The diagnostic pathway typically includes:

Blood tests: Liver function tests may show elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST), though normal LFTs do not exclude NAFLD. A comprehensive metabolic panel should include fasting glucose, HbA1c, and lipid profile. It is essential to exclude other causes of liver disease, including:

• Alcohol intake: Take a careful history; UK low-risk guidance is ≤14 units per week, spread over at least three days, with several alcohol-free days

• Viral hepatitis: Hepatitis B and C serology

• Autoimmune liver disease: Autoantibodies (ANA, SMA, LKM)

• Medications: Review for hepatotoxic drugs

• Metabolic and genetic conditions: As clinically indicated

Imaging: Ultrasound scanning is the first-line imaging modality for detecting hepatic steatosis, though it has limited sensitivity for detecting fat content below 20–30%.

Fibrosis risk assessment: NICE NG49 recommends using non-invasive scoring systems to stratify patients according to their risk of advanced fibrosis. First-line tools include:

• FIB-4 score: Use age-specific thresholds (low risk <1.3 if under 65 years; <2.0 if 65 years or older)

• NAFLD Fibrosis Score (NFS)

If the result is indeterminate or suggests increased risk, offer Enhanced Liver Fibrosis (ELF) blood test as a second-line assessment. Transient elastography (FibroScan) may also be considered to assess liver stiffness, a marker of fibrosis. Those identified as high-risk should be referred to hepatology services for specialist assessment. Liver biopsy remains the gold standard for definitive diagnosis and staging but is reserved for selected cases due to its invasive nature and is typically performed under specialist guidance.

Managing Fatty Liver When You Have Prediabetes

The cornerstone of managing both prediabetes and NAFLD is lifestyle modification, which can simultaneously improve insulin sensitivity, reduce hepatic fat accumulation, and prevent progression to type 2 diabetes and advanced liver disease. Evidence demonstrates that weight loss of 7–10% of body weight can lead to resolution of NASH, and ≥10% may achieve regression of fibrosis. Even modest weight loss of 5% can significantly reduce liver fat content and improve metabolic parameters. Weight loss should be gradual and sustainable (approximately 0.5–1 kg per week); very rapid weight loss should be avoided.

Dietary interventions should focus on:

• Caloric restriction to achieve gradual, sustainable weight loss

• Reducing refined carbohydrates and added sugars, particularly fructose-containing beverages and foods

• Increasing dietary fibre through vegetables, fruits, whole grains, and legumes

• Choosing healthy fats such as those found in olive oil, nuts, and oily fish

• Limiting saturated fats from processed foods and fatty meats

• Moderating portion sizes and avoiding late-evening eating

The Mediterranean diet pattern has robust evidence supporting its benefits for both metabolic health and liver fat reduction.

Alcohol: Adhere to UK Chief Medical Officers' low-risk drinking guidelines: ≤14 units per week, spread over at least three days, with several alcohol-free days each week. Avoid binge drinking.

Physical activity is equally important. The UK Chief Medical Officers' Physical Activity Guidelines recommend at least 150 minutes of moderate-intensity aerobic activity weekly (such as brisk walking, cycling, or swimming), combined with muscle-strengthening activities on two or more days per week. Exercise improves insulin sensitivity independent of weight loss and has direct beneficial effects on hepatic fat metabolism.

Medical management for prediabetes: Individuals with non-diabetic hyperglycaemia should be offered referral to the NHS Diabetes Prevention Programme (NHS DPP), which provides structured, evidence-based lifestyle support. According to NICE guideline PH38, metformin may be considered for adults at high risk of progression to type 2 diabetes if lifestyle interventions alone are insufficient, particularly in those with a BMI ≥35 kg/m² or other risk factors.

Medical management for NAFLD: There are currently no licensed pharmacological treatments specifically for NAFLD in the UK. Management of associated cardiovascular risk factors is essential. Statins should not be withheld due to concerns about liver disease and may be beneficial for cardiovascular risk reduction. Vitamin E and pioglitazone have shown some benefit in non-alcoholic steatohepatitis in clinical trials; however, their use is off-label, typically reserved for biopsy-proven NASH with advanced fibrosis, and should only be initiated under specialist hepatology care after discussion of risks and benefits.

Monitoring and follow-up should be individualised and may include:

• Weight and waist circumference: Regular measurement

• Blood glucose control: At least annual HbA1c for those with non-diabetic hyperglycaemia

• Liver function tests: Frequency tailored to individual risk

• Lipid profile and cardiovascular risk factors: As per standard guidance

• Fibrosis risk re-assessment: NICE NG49 recommends re-assessing fibrosis risk approximately every three years in adults with NAFLD using non-invasive tests

When to seek medical advice: Patients should contact their GP if they experience new symptoms such as persistent abdominal pain, unexplained weight loss, jaundice (yellowing of skin or eyes), or significant fatigue. Regular engagement with healthcare services, including practice nurses and dietitians, supports sustained lifestyle changes and appropriate monitoring. Referral to specialist hepatology services is indicated for those with evidence of advanced fibrosis (based on non-invasive scoring), diagnostic uncertainty, or failure to improve with lifestyle measures. The NHS Diabetes Prevention Programme offers structured support for individuals with prediabetes and can be an invaluable resource for achieving and maintaining lifestyle changes that benefit both conditions.

Frequently Asked Questions