Non-alcoholic fatty liver disease (NAFLD) typically occurs in persons with obesity. But now NAFLD is increasingly being observed in those with normal body mass index (BMI) and has been termed “lean NAFLD”. Although the disease is less severe in the lean, it progresses through a similar spectrum of diseases and shares similar comorbid metabolic disorders like type 2 diabetes, dyslipidemia and metabolic syndrome as in NAFLD in persons with obesity.¹

To determine the incidence of new onset type 2 diabetes among people with lean NAFLD, a meta-analysis of studies was carried out.2 Published studies on lean NAFLD up to December 2022 were screened after a thorough search of PubMed, Scopus, Cochrane and Web of Science databases and 16 observational studies were selected for the final meta-analysis.

Out of the 304,975 adult patients included, 7.7% had lean NAFLD. Over a follow-up period of 5.05 years, there were nearly 1300 cases of incident diabetes.

Analysis of data published in the journal Diabetes Research and Clinical Practice showed that participants with lean NAFLD were twice more likely to develop incident diabetes compared to those who did not have NAFLD with a hazard ratio of 2.72. The adjusted HR of incident diabetes in subjects with overweight/obesity but without NAFLD was 1.32. While among the participants with overweight/obesity and NAFLD, the aHR was 2.98. Patients with NAFLD were nearly 3.5 times more likely to develop type 2 diabetes if they had advanced high NAFLD fibrosis scores with HR of 3.48.

This study shows that the risk of type 2 diabetes was higher in people with lean NAFLD compared to the lean without NAFLD. The risk of developing diabetes was equivalent between the lean and overweight/obese individuals with NAFLD suggesting that NAFLD, more than overweight/obesity, was a risk factor for type 2 diabetes in this patient group. Patients with increasing NAFLD fibrosis score were at greater risk.

Reference

1. Ahadi M, et al. A review of non-alcoholic fatty liver disease in non-obese and lean individuals. J Gastroenterol Hepatol. 2021 Jun;36(6):1497-1507.
2. Gao Y, et al. Lean nonalcoholic fatty liver disease and risk of incident type 2 diabetes mellitus: A literature review and meta-analysis. Diabetes Res Clin Pract. 2023 Jun;200:110699. doi: 10.1016/j.diabres.2023.110699.