Metabolic Dysfunction-Associated Steatotic Liver Disease in Type 2 Diabetes Mellitus: A Review and Position Statement of the Fatty Liver Research Group of the Korean Diabetes Association

Abstract

Since the role of the liver in metabolic dysfunction, including type 2 diabetes mellitus, was demonstrated, studies on non-alcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated fatty liver disease (MAFLD) have shown associations between fatty liver disease and other metabolic diseases. Unlike the exclusionary diagnostic criteria of NAFLD, MAFLD diagnosis is based on the presence of metabolic dysregulation in fatty liver disease. Renaming NAFLD as MAFLD also introduced simpler diagnostic criteria. In 2023, a new nomenclature, steatotic liver disease (SLD), was proposed. Similar to MAFLD, SLD diagnosis is based on the presence of hepatic steatosis with at least one cardiometabolic dysfunction. SLD is categorized into metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction and alcohol-related/-associated liver disease, alcoholrelated liver disease, specific etiology SLD, and cryptogenic SLD. The term MASLD has been adopted by a number of leading national and international societies due to its concise diagnostic criteria, exclusion of other concomitant liver diseases, and lack of stigmatizing terms. This article reviews the diagnostic criteria, clinical relevance, and differences among NAFLD, MAFLD, and MASLD from a diabetologist's perspective and provides a rationale for adopting SLD/MASLD in the Fatty Liver Research Group of the Korean Diabetes Association.

Keywords: Diabetes mellitus, type 2; Metabolic dysfunction-associated steatotic liver disease; Non-alcoholic fatty liver disease.

Fig. 1.

Diagnostic criteria of non-alcoholic fatty liver disease (NAFLD), metabolic dysfunction-associated fatty liver disease (MAFLD), and metabolic dysfunction-associated steatotic liver disease (MASLD). SLD, steatotic liver disease; T2DM, type 2 diabetes mellitus; WC, waist circumference; BP, blood pressure; TG, triglyceride; HDL-C, high-density lipoprotein cholesterol; HOMA-IR, homeostasis model assessment of insulin resistance; Hs-CRP, high-sensitivity C-reactive protein; BMI, body mass index; MetALD, metabolic dysfunction– and alcohol-related/-associated liver disease; ALD, alcohol-related liver disease.

Fig. 2.

Liver pathology of alcoholic steatohepatitis (ASH) and metabolic dysfunction-associated steatohepatitis (MASH). (A, B) The liver biopsy specimens in the top row came from a patient with alcoholic cirrhosis during liver transplantation. They show (A) cholestasis (arrowhead), (B) ballooned hepatocytes containing Malloy-Denk bodies (arrow), and focal necrosis associated with prominent inflammatory cell infiltration and fibrosis (hematoxylin and eosin stain [H&E]). (C, D) The liver biopsy specimens in the bottom row came from a patient with obesity during bariatric surgery. It shows macrovesicular zone 3 steatosis accompanied by lobular inflammation. (C) Ballooning degeneration (arrowhead) is observed, it is characterized by enlarged and swollen hepatocytes with granular material in the cytoplasm, which represents collapsed cytoskeleton. (D) Neutrophilic satellitosis (circle) and Mallory’s hyaline, clumps of ropy eosinophilic material in hepatocyte cytoplasm representing misfolded and aggregated keratin filaments (arrow), are also present. ASH and MASH are pathologically difficult to distinguish (H&E; A and C, 100×; B and D, 200×).

Fig. 3.

Algorithm for steatotic liver disease (SLD) evaluation in patients with type 2 diabetes mellitus (T2DM). BMI, body mass index; WC, waist circumference; BP, blood pressure; TG, triglycerides; HDL-C, high-density lipoprotein cholesterol; FIB-4, fibrosis- 4; VCTE, vibration-controlled transient elastography; ELF, enhanced liver fibrosis; MRE, magnetic resonance elastography. aHigher cutoffs for patients aged >65.