Preface: Diabetes and liver disease are prevalent chronic conditions in China. They often interact in terms of pathogenesis, clinical manifestations, and treatment targets, acting as mutual risk factors. Joint management can alleviate the disease burden. To support the development of co-management of diabetes and liver disease in China, this journal, in collaboration with the CDL (China Diabetes and Liver Disease Co-management Action Plan), launches the CDL Literature Monthly Review column. Each month, we share relevant research on the mechanisms and treatment advancements of diabetes combined with liver disease, inviting experts in the field to provide commentary. This aims to offer insights and assistance to researchers and frontline medical professionals in scientific research and clinical practice.
This issue features six clinical and basic research articles on diabetes, fatty liver disease, chronic hepatitis B, and end-stage liver disease. The invited experts for this issue are Professor Wei Li from the First Affiliated Hospital of Bengbu Medical University, Professor Chao Sun from Tianjin Medical University General Hospital, and Professor Hongshan Li from Ningbo No.2 Hospital.
Review Experts:Professor Wei Li, TheFirst Affiliated Hospital of Bengbu Medical University
01. Protein-truncating Variants in BSN Are Associated with Severe Adult-onset Obesity, Type 2 Diabetes, and Fatty Liver Disease
Zhao Y, Chukanova M, Kentistou KA, et al. Nat Genet, 2024, 56(4): 579-584.
Obesity is a major risk factor for many common diseases and has a significant genetic component. This study conducted an exome-wide association analysis on the exome sequencing data of 587,027 individuals and identified rare loss-of-function mutations in two genes, BSN and APBA1, which have a much greater effect on obesity than known obesity-related genes (e.g., MC4R). Unlike most other obesity-related genes, the rare mutations in BSN and APBA1 are not associated with childhood obesity; their obesity risk does not manifest until adulthood. Additionally, BSN protein-truncating variants (PTVs) amplify the effect of common genetic variations associated with BMI, with the polygenic score’s effect on BMI being twice as strong in BSN PTV carriers compared to non-carriers. The study also examined the plasma proteomic characteristics of BSN PTV carriers and the functional impact of BSN deficiency on human induced pluripotent stem cell-derived hypothalamic neurons. The results suggest that adult-onset obesity is related to the degradation of synaptic function.
Commentary: This study used exome-wide association studies (ExWAS) on the exome sequencing (WES) data of 587,027 individuals to discover that rare PTVs in BSN and APBA1 are associated with significant increases in adult BMI and high risks of adult and severe obesity, with effects much greater than known obesity-related genes. Rare PTVs in BSN are also associated with high risks of type 2 diabetes (T2DM) and non-alcoholic fatty liver disease (NAFLD). The study confirmed the association with adult BMI in independent cohorts, and the common variant signals of APBA1 and BSN supported this association. In the UK Biobank, 65 BSN PTV carriers showed no difference in childhood obesity-related traits compared to non-carriers, indicating that APBA1 and BSN primarily contribute to adult-onset obesity. Linear regression models tested the interaction between the common variant polygenic score (PGS) and rare variant carrier status for BMI, revealing that BSN PTV significantly altered the effect, while APBA1 PTV did not. The study also used existing proteomic data, identifying significant associations between plasma protein levels and BSN PTV carriers. Single-nucleus RNA sequencing (snRNA-seq) of 61,016 hypothalamic neurons (32,198 BSN+/−, 28,818 wild-type) showed downregulation of NTNG1 in four clusters. NTNG1, closely related to bassoon protein in the presynaptic active zone, is critical for synaptic function. This implies that adult-onset obesity might be linked to APBA1 and BSN’s roles in aging-related neurosecretory vesicle dysfunction and neurodegeneration.
In summary, rare genetic disruptions in APBA1 and BSN have a greater impact on adult BMI and obesity risk than any previously described obesity risk genes. Rare PTVs in APBA1 and BSN seem to confer a risk of adult-onset obesity, potentially due to general dysregulation of neurodevelopment, neurogenesis, and neuronal oxidative phosphorylation in the central feeding circuit.
02. Association of GLP-1 Receptor Agonists and Hepatocellular Carcinoma Incidence and Hepatic Decompensation in Patients with Type 2 Diabetes
Wang L, Berger NA, Kaelber DC, et al. Gastroenterology, 2024. doi: 10.1053/j.gastro.2024.04.029
Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are FDA-approved drugs for treating T2DM and exhibit multiple effects against HCC risk factors. This study assessed the association between GLP-1RAs and the risk of HCC in real-world populations. The results showed that GLP-1RAs are associated with a reduced risk of HCC and hepatic decompensation in T2DM patients compared to other antidiabetic drugs, providing evidence for future studies on potential mechanisms and clinical applications.
The study retrospectively included 1,890,020 patients diagnosed with T2DM who were treated with GLP-1RAs or other non-GLP-1RA antidiabetic drugs and had no prior HCC diagnosis. Over a five-year follow-up, the study compared the first HCC diagnosis and hepatic decompensation events between GLP-1RA and other antidiabetic drug cohorts using Kaplan-Meier survival analysis and calculated hazard ratios (HRs) with 95% confidence intervals (CIs). GLP-1RAs were associated with a lower risk of HCC compared to insulin (HR: 0.20, 95% CI: 0.14-0.31), sulfonylureas (HR: 0.39, 95% CI: 0.21-0.69), and metformin (HR: 0.63, 95% CI: 0.26-1.50). GLP-1RAs were also significantly associated with reduced risk of hepatic decompensation compared to six other antidiabetic drugs. Risk reduction was observed in patients with and without fatty liver at different stages, with a more substantial effect in those without liver disease. Similar results were found in patients with or without obesity, alcohol use disorder, or tobacco use disorder. GLP-1RA combination therapy was associated with lower risks of HCC and hepatic decompensation compared to monotherapy.
Commentary: HCC remains a leading cause of cancer deaths. Risk factors include obesity, T2DM, metabolic-associated steatotic liver disease (MASLD), metabolic-associated steatohepatitis (MASH), alcohol, and tobacco use. This study evaluated the relationship between GLP-1RAs, a T2DM treatment, and the risk of HCC in a real-world population.
The authors used the TriNetX platform to retrospectively study 1,890,020 T2DM patients from 63 healthcare institutions across 50 US states from January 2013 to February 2019. They found that combination therapy of GLP-1RAs with other antidiabetic drugs, including insulin, sulfonylureas, metformin, DPP-4 inhibitors, SGLT2 inhibitors, and thiazolidinediones, was more effective in reducing the risks of HCC and hepatic decompensation compared to monotherapy. Monotherapy with GLP-1RAs significantly reduced hepatic decompensation events but did not significantly impact HCC incidence. GLP-1RA and insulin combination therapy was more effective in preventing HCC than insulin alone, but GLP-1RAs could not reverse the harmful impact of insulin on HCC risk, as combined therapy patients still had an increased risk of HCC and hepatic decompensation. The study found that GLP-1RAs were associated with reduced HCC incidence in patients without MASLD, MASH, liver fibrosis, or cirrhosis compared to non-GLP-1RA drugs. Conversely, in patients with these liver diseases, GLP-1RAs were associated with lower HCC incidence compared to insulin but not other antidiabetic drugs. GLP-1RAs were also associated with lower hepatic decompensation risk in patients with and without these liver diseases, with a more significant effect in those without the diseases. The study also found that GLP-1RAs were associated with reduced risks of HCC and hepatic decompensation in non-obese, non-smoking patients compared to insulin, metformin, DPP-4 inhibitors, and sulfonylureas.
However, the study has limitations: as a retrospective observational study, causality cannot be inferred. Additionally, data and analytical tool limitations precluded direct discovery of the underlying mechanisms by which GLP-1RAs affect HCC. Further preclinical and clinical research is needed to explore potential mechanisms and support the clinical use of GLP-1RAs for HCC prevention.
Review Expert:Professor Chao Sun, Tianjin Medical University General Hospital
03. PNPLA3 rs738409, Age, Diabetes, Sex, and Advanced Fibrosis Jointly Contribute to the Risk of Major Adverse Liver Outcomes in Metabolic-associated Steatotic Liver Disease
Chalasani N, Vilar-Gomez E, Loomba R, et al. Hepatology, 2024. doi: 10.1097/HEP.0000000000000896.
Variations in patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 are associated with the occurrence and progression of steatotic liver disease (SLD). US scientists studied the relationship between PNPLA3 and the development of major adverse liver outcomes (MALO) and how modifiable and non-modifiable factors influence this relationship. The results showed that the detrimental effect of PNPLA3 rs738409 on MALO risk is significantly affected by advanced fibrosis (AF), age, T2DM, and sex.
The MASLD CRN study included 2,075 biopsy-confirmed MASLD adult patients and conducted prospective follow-up. During an average follow-up of 4.3 years, 104 MALOs were recorded. The PNPLA3 G allele (adjusted sHR: 1.4, 95% CI: 1.09-1.8), AF (adjusted sHR: 7.8, 95% CI: 4.4-13.8), age > 60 years (adjusted sHR: 2.9, 95% CI: 1.3-6.8), and T2DM (adjusted sHR: 2.8, 95% CI: 1.8-4.2) were associated with MALO. Among AF patients, those carrying the G allele had the highest cumulative incidence of MALO (85%), while non-carriers had a cumulative incidence of 53% (P = 0.03), with an interaction P-value < 0.01. Compared to controls, the strength of the association between PNPLA3 and MALO increased significantly in patients over 60 years old (sHR: 2.1, 95% CI: 1.5-2.8), female (sHR: 1.4, 95% CI: 1.1-1.9), with AF (sHR: 1.9, 95% CI: 1.5-2.4), or with T2DM (sHR: 2.1, 95% CI: 1.5-2.8), with an interaction P-value < 0.01.
Commentary: This multicenter prospective study included a large sample of biopsy-confirmed MASLD patients with comprehensive follow-up records, providing the first comprehensive assessment of the relationship between PNPLA3 genetic polymorphisms and potential long-term complications. Given the lack of clinical guidelines or consensus on screening for PNPLA3 rs738409, healthcare professionals should pay special attention to MASLD patients with advanced fibrosis, advanced age, or concurrent T2DM. Systematic screening of patients carrying the G allele and targeted nutritional assessment/intervention, medication treatment, and proper control of related risk factors are recommended.
Although this study provides clues about the relationship between PNPLA3 and various adverse liver outcomes/events, this phenomenon seems more pronounced in female patients. However, there are design limitations, such as the lack of calibration for individual socioeconomic status and lifestyle. Additionally, most of the study population were non-Hispanic whites, affecting the results’ generalizability to other ethnic and racial groups. Overall, from the perspective of genetic variation, planning and designing clinical trials for drug development targeting MASLD patients could be highly efficient.
04. Body Weight Variability and the Risk of Liver-related Outcomes in Type 2 Diabetes and Steatotic Liver Disease: A Cohort Study
Leite NC, Cardoso CRL, Villela-Nogueira CA, et al. Obesity (Silver Spring), 2024, 32(6): 1210-1218.
This study evaluated the impact of body weight variability (BWV) on liver-related adverse outcomes in patients with T2DM and MASLD. The results showed that increased BWV is associated with adverse liver outcomes in T2DM and MASLD patients; however, those who exercise regularly do not face this risk.
A total of 549 patients with T2DM and MASLD were assessed for BWV parameters during the initial two-year follow-up. Multivariate logistic regression analysis evaluated the relationship between increased BWV and liver outcomes (clinical cirrhosis or transient elastography liver stiffness measurement > 15 kPa, median time of 7 years). Interaction/subgroup analysis was performed based on participants’ physical activity levels during the initial two years. During a median additional follow-up of 9.7 years, 34 adverse outcomes occurred, including 14 cases of clinical cirrhosis and 20 cases with liver stiffness > 15 kPa. For each standard deviation increase in weight standard deviation and mean actual variability, the odds of adverse liver outcomes increased by 52% (95% CI: 4%-128%). Additionally, increased BWV was associated with higher adverse outcome risks only in individuals with prolonged sedentary behavior.
Commentary: Weight loss can effectively improve liver histopathology and cardiometabolic abnormalities in MASLD patients. BWV, describing weight fluctuations, can reflect changes in body composition and metabolic homeostasis and has been previously reported to be associated with adverse cardiovascular events and mortality in populations. This study further confirmed that increased BWV is associated with several clinical “hard” outcomes—such as progression to cirrhosis—in MASLD patients with concurrent T2DM. Interestingly, effective physical activity appears to mitigate these negative effects. Moreover, this effect exists independently of average weight or weight loss, eliminating these confounding factors.
The study design has some areas for improvement, such as difficulty distinguishing whether weight changes are voluntary or involuntary, lack of dietary pattern information during follow-up, reliance on self-reported physical activity questionnaires, and the majority of participants being middle-aged diabetics under long-term care at tertiary university-affiliated hospitals, which may affect the representativeness and generalizability of the findings.
Review Expert:Professor Hongshan Li, Ningbo No.2 Hospital
05. Liver Lipidomics Analysis Revealed the Protective Mechanism of Zuogui Jiangtang Qinggan Formula in Type 2 Diabetes Mellitus with Non-alcoholic Fatty Liver Disease
Zhou M, Liu X, Wu Y, et al. J Ethnopharmacol, 2024, 329: 118160.
Hepatic steatosis is a hallmark of non-alcoholic fatty liver disease (NAFLD) and a major global health issue. Recently, liver lipidomics has gained attention, highlighting the role of Traditional Chinese Medicine (TCM) in alleviating such diseases by regulating lipid metabolism. Zuogui Jiangtang Qinggan Formula (ZGJTQGF) is a long-term TCM treatment for T2DM with NAFLD, but its mechanism in regulating lipid metabolism is unclear.
To elucidate the mechanism of ZGJTQGF’s impact on lipid metabolism in T2DM with NAFLD, this study used db/db mice to establish a T2DM with NAFLD model. The assessments included HE staining, Oil Red O staining, biochemical tests, liver lipidomics, and Western blotting. The results showed that ZGJTQGF improved lipid disorders of TG, DG, PC, and PE in T2DM with NAFLD and enhanced the de novo lipogenesis pathway, improving fatty acid and cholesterol metabolism.
ZGJTQGF significantly reduced mouse body weight, lowered fasting blood glucose (FBG), and improved glucose tolerance. HE and Oil Red O staining, along with biochemical and liver lipidomics analyses, confirmed ZGJTQGF’s efficacy in ameliorating liver steatosis and lipid metabolism disorders. Lipidomics identified significant changes in 1,571 lipids in the model group, mainly showing upregulation of TG and DG and downregulation of PC and PE levels. After ZGJTQGF treatment, 496 lipids were modulated, with increased PC and PE levels and decreased TG and DG levels, indicating significant improvement in lipid metabolism in T2DM with NAFLD. Additionally, ZGJTQGF affected proteins related to lipid synthesis, emphasizing its anti-steatosis effects through liver lipidomics changes and providing new insights into the pathogenesis of liver steatosis.
Commentary: This animal study evaluated the efficacy and mechanism of ZGJTQGF in treating T2DM with NAFLD using a db/db mouse model. It systematically assessed ZGJTQGF’s effects on liver lipid deposition, liver function, and insulin resistance, using lipidomics and Western blot (WB) to explore the mechanism of ZGJTQGF’s improvement of lipid metabolism in T2DM with NAFLD mice.
The study showed that ZGJTQGF could improve liver lipid deposition, liver function, and insulin resistance in T2DM with NAFLD mice. Lipidomics analysis indicated that ZGJTQGF significantly upregulated TG and DG levels and downregulated PC and PE levels in the liver tissue of T2DM with NAFLD mice. WB results showed that ZGJTQGF significantly regulated the expression of pAMPK, ACC, SREBP1, LDLR, and PPAR-a in the liver tissue. This study not only confirmed the efficacy of ZGJTQGF in treating T2DM with NAFLD but also elucidated its mechanism in improving lipid metabolism, laying a foundation for its further development and application.
However, the study has some limitations, such as the relatively weak research on the mechanism, unable to clarify the specific targets and pathways of ZGJTQGF in improving lipid metabolism in T2DM with NAFLD. Moreover, ZGJTQGF contains 10 herbs with complex components, and the pharmacological basis for improving lipid metabolism in T2DM with NAFLD is unclear, requiring further in-depth research. Finally, as db/db mice are genetically deficient, it remains debatable whether they can fully model the disease characteristics of human T2DM with NAFLD.
06. Love-hate Relationship between Hepatitis B Virus and Type 2 Diabetes: A Mendelian Randomization Study
Yu Y, Tong K, Hu G, et al. Front Microbiol, 2024, 15: 1378311.
The impact of HBV on T2DM risk remains controversial. This study obtained single nucleotide polymorphism data for chronic hepatitis B (CHB), liver fibrosis, cirrhosis, and T2DM from the BioBank Japan Project, European Bioinformatics Institute, and FinnGen. Using Mendelian randomization (MR), it evaluated the causal relationship between HBV and T2DM. The results suggest that CHB may serve as a protective factor against T2DM, but its efficacy is influenced by viral load and disease stage. This protective effect weakens or disappears with reduced viral load and transitions to a risk factor as liver fibrosis and cirrhosis progress.
The inverse variance-weighted method was the primary MR analysis approach. To assess horizontal pleiotropy and heterogeneity, the study conducted MR-Egger intercept analysis and Cochran’s Q test and used sensitivity analysis to evaluate the robustness of MR results. MR analysis showed that CHB was associated with reduced T2DM genetic susceptibility (OR: 0.975, 95% CI: 0.962-0.989, P < 0.001), while cirrhosis (OR: 1.021, 95% CI: 1.007-1.036, P = 0.004) and combined liver fibrosis and cirrhosis (OR: 1.015, 95% CI: 1.002-1.028, P = 0.020) were associated with increased T2DM genetic susceptibility. MR-Egger intercept showed no horizontal pleiotropy (P > 0.05), Cochran’s Q test showed no heterogeneity (P > 0.05), and sensitivity analysis indicated robust results.
Commentary: This Mendelian randomization study evaluated the relationship between HBV and T2DM. It used single nucleotide polymorphism data from the BioBank Japan Project, European Bioinformatics Institute, and FinnGen and applied MR methods to assess the relationship between HBV and T2DM, systematically evaluating the impact of CHB viral load and different disease stages on T2DM.
The study found that CHB could reduce genetic susceptibility to T2DM, suggesting that HBV infection might lower T2DM risk. However, this protective effect is closely related to HBV viral load and diminishes with decreasing viral load. The study also found that liver fibrosis and cirrhosis were associated with increased genetic susceptibility to T2DM. The comprehensive analysis of different stages of HBV infection on T2DM provides insights into the relationship between HBV infection and T2DM.
However, as an MR study, it has limitations. Firstly, the data set came from a specific ethnic population, leading to uncertainty about the generalizability of the results to other ethnicities. Secondly, due to data set limitations, the study could not group by HBV viral load, making it difficult to precisely evaluate the relationship between different HBV loads and T2DM genetic susceptibility. Thirdly, the study used non-specific liver fibrosis and cirrhosis data, limiting the ability to fully elucidate the impact of HBV-related liver fibrosis and cirrhosis on T2DM risk. Therefore, this study does not resolve the current controversy on the impact of HBV on T2DM risk. Future research should focus on human genome-wide studies, using more comprehensive data to conduct MR analyses across different ethnicities. Additionally, large-sample, high-quality, multicenter clinical studies are needed to explore the impact of different viral loads and stages of HBV infection on T2DM.
