The persistence of fatty liver has a differential impact on the development of diabetes: The Kangbuk Samsung Health Study

Insulin Resistance, Non-Alcoholic Fatty Liver Disease and Type 2 Diabetes Mellitus: Clinical and Experimental Perspective

It has been generally accepted that insulin resistance (IR) and reduced insulin secretory capacity are the basic pathogenesis of type 2 diabetes mellitus (T2DM). In addition to genetic factors, the persistence of systemic inflammation caused by obesity and the associated threat of lipotoxicity increase the risk of T2DM. In particular, the main cause of IR is obesity and subjects with T2DM have a higher body mass index (BMI) than normal subjects according to recent studies. The prevalence of T2DM with IR has increased with increasing BMI during the past three decades. According to recent studies, homeostatic model assessment of IR was increased compared to that of the 1990s. Rising prevalence of obesity in Korea have contributed to the development of IR, non-alcoholic fatty liver disease and T2DM and cutting this vicious cycle is important. My colleagues and I have investigated this pathogenic mechanism on this theme through clinical and experimental studies over 20 years and herein, I would like to summarize some of our studies with deep gratitude for receiving the prestigious 2023 Sulwon Award.

Changes in Fatty Liver Disease and Incident Diabetes Mellitus in Young Korean Adults

INTRODUCTION

This study sought to assess the association between the changes in nonalcoholic fatty liver disease (NAFLD) and risk of type 2 diabetes in young individuals with prediabetes.

METHODS

Data from the Korean National Health Insurance System database were collected from 2009 to 2019 and analyzed in 2022. A total of 446,813 young adults aged 20-39 years with prediabetes who underwent two National Health Screening examinations from 2009 to 2012 were followed up. NAFLD was defined as a fatty liver index≥60 without liver disease or history of alcohol abuse. Multivariable Cox proportional hazards regression was used to calculate the HR and CIs for type 2 diabetes according to NAFLD changes.

RESULTS

During a median follow-up of 8.3 years, 26,464 (5.9%) young individuals developed type 2 diabetes. Multivariable adjusted HR of type 2 diabetes according to the NAFLD change was 5.38 (95% CI 5.08-5.70) in individuals with persistent NAFLD when compared to those who never had NAFLD. Even in individuals who were consistently nonobese, resolved NAFLD, new NAFLD, and persistent NAFLD were associated with>3-fold increased risk of type 2 diabetes compared to nonobese individuals without NAFLD. The risk of type 2 diabetes also increased in obese individuals without NAFLD by 2-fold when compared to nonobese individuals without NAFLD.

CONCLUSIONS

NAFLD that either existed persistently or ever existed plays a critical role in the development of type 2 diabetes in young adults with or without obesity. Nonobese individuals with NAFLD warrant special attention.

Global epidemiology of type 2 diabetes in patients with NAFLD or MAFLD: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD) shares common pathophysiological mechanisms with type 2 diabetes, making them significant risk factors for type 2 diabetes. The present study aimed to assess the epidemiological feature of type 2 diabetes in patients with NAFLD or MAFLD at global levels.

METHODS

Published studies were searched for terms that included type 2 diabetes, and NAFLD or MAFLD using PubMed, EMBASE, MEDLINE, and Web of Science databases from their inception to December 2022. The pooled global and regional prevalence and incidence density of type 2 diabetes in patients with NAFLD or MAFLD were evaluated using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

RESULTS

A total of 395 studies (6,878,568 participants with NAFLD; 1,172,637 participants with MAFLD) from 40 countries or areas were included in the meta-analysis. The pooled prevalence of type 2 diabetes among NAFLD or MAFLD patients was 28.3% (95% confidence interval 25.2-31.6%) and 26.2% (23.9-28.6%) globally. The incidence density of type 2 diabetes in NAFLD or MAFLD patients was 24.6 per 1000-person year (20.7 to 29.2) and 26.9 per 1000-person year (7.3 to 44.4), respectively.

CONCLUSIONS

The present study describes the global prevalence and incidence of type 2 diabetes in patients with NAFLD or MAFLD. The study findings serve as a valuable resource to assess the global clinical and economic impact of type 2 diabetes in patients with NAFLD or MAFLD.

Endpoints in NASH Clinical Trials: Are We Blind in One Eye?

This narrative review aims to illustrate the notion that nonalcoholic steatohepatitis (NASH), recently renamed metabolic dysfunction-associated steatohepatitis (MASH), is a systemic metabolic disorder featuring both adverse hepatic and extrahepatic outcomes. In recent years, several NASH trials have failed to identify effective pharmacological treatments and, therefore, lifestyle changes are the cornerstone of therapy for NASH. with this context, we analyze the epidemiological burden of NASH and the possible pathogenetic factors involved. These include genetic factors, insulin resistance, lipotoxicity, immuno-thrombosis, oxidative stress, reprogramming of hepatic metabolism, and hypoxia, all of which eventually culminate in low-grade chronic inflammation and increased risk of fibrosis progression. The possible explanations underlying the failure of NASH trials are also accurately examined. We conclude that the high heterogeneity of NASH, resulting from variable genetic backgrounds, exposure, and responses to different metabolic stresses, susceptibility to hepatocyte lipotoxicity, and differences in repair-response, calls for personalized medicine approaches involving research on noninvasive biomarkers. Future NASH trials should aim at achieving a complete assessment of systemic determinants, modifiers, and correlates of NASH, thus adopting a more holistic and unbiased approach, notably including cardiovascular-kidney-metabolic outcomes, without restricting therapeutic perspectives to histological surrogates of liver-related outcomes alone.

Repeated detection of non-alcoholic fatty liver disease increases the incidence risk of type 2 diabetes in young adults

AIM

This study aimed to investigate the effects of repeated detection of non-alcoholic fatty liver disease (NAFLD) on the incidence risk of type 2 diabetes in young adults.

MATERIALS AND METHODS

In this nationwide population-based observational study using data from the Korean National Health Insurance Service, approximately 1 125 015 young adults aged 20-39 years who underwent health screening four times between 2009 and 2013 were included. NAFLD was defined as a fatty liver index (FLI) of ≥60. Repeated detection of NAFLD scores was defined as the number of times the participants met the criteria for NAFLD (0-4). To account for the degree of repeated detection of NAFLD, weighted repeated NAFLD scores were scaled as a sum by assigning points (0 points for FLI <30, 1 point for 30 ≤ FLI < 60, and 2 points for FLI ≥60) ranging from 0 to 8 points.

RESULTS

The multivariable-adjusted hazard ratios of type 2 diabetes associated with repeated detection of NAFLD scores of 1, 2, 3 and 4 were 2.74 (95% confidence interval 2.57-2.921), 3.45 (3.221-3.694), 4.588 (4.303-4.892) and 6.126 (5.77-6.504), respectively. The incidence risk of type 2 diabetes increased significantly with repeated detection of the NAFLD score. In the analysis of the weighted repeated NAFLD score, the hazard ratios for the incidence of type 2 diabetes showed a significant continuous positive linear association with increasing scores.

CONCLUSIONS

Repeated detection of NAFLD influenced the incidence risk of type 2 diabetes in young adults, and a higher degree of repeated detection of NAFLD was independently associated with the risk of type 2 diabetes in young adults.

Fatty Liver Change in Older Adults as an Important Risk Factor for Type 2 Diabetes: A Nationwide Cohort Study

OBJECTIVE

To examine the association between changes in fatty liver disease (FLD) over time and the risk of type 2 diabetes in elderly individuals with prediabetes.

METHODS

A total of 156,984 elderly individuals with prediabetes who underwent national health screening in 2009 and 2011 were followed up through December 31, 2019. The FLD status was defined as a change in the fatty liver index. Prediabetes was defined as impaired fasting glucose levels at baseline. Multivariable Cox proportional hazards regression was used to calculate the hazard ratio and CIs for type 2 diabetes according to the changes in FLD.

RESULTS

During a median of 8.35 years of follow-up, type 2 diabetes developed in 29,422 (18.7%) elderly individuals with prediabetes. Multivariable adjusted hazard ratio of type 2 diabetes according to FLD change was 2.22 (95% CI, 2.11 to 2.34) in individuals with persistent FLD compared with those who have never had FLD. Although overall weight loss of 5% or more was associated with a 7% lower risk of type 2 diabetes in total participants, fatty liver status was important. Even with weight loss, those with a history of fatty liver-resolved FLD, new FLD, or persistent FLD-had an increased risk of type 2 diabetes. The risk of type 2 diabetes did not increase in individuals with sustained FLD-free status, regardless of weight change.

CONCLUSION

The presence and change of FLD are important factors for the development of type 2 diabetes in elderly individuals with prediabetes.

Clinical Classification of Obesity and Implications for Metabolic Dysfunction-Associated Fatty Liver Disease and Treatment

Obesity,and metabolic dysfunction-associated fatty liver disease (MAFLD) have reached epidemic proportions globally. Obesity and MAFLD frequently coexist and act synergistically to increase the risk of adverse clinical outcomes (both hepatic and extrahepatic). Type 2 diabetes mellitus (T2DM) is the most important risk factor for rapid progression of steatohepatitis and advanced fibrosis. Conversely, the later stages of MAFLD are associated with an increased risk of T2DM incident. According to the proposed criteria, MAFLD is diagnosed in patients with liver steatosis and in at least one in three: overweight or obese, T2DM, or signs of metabolic dysregulation if they are of normal weight. However, the clinical classification and correlation between obesity and MAFLD is more complex than expected. In addition, treatment for obesity and MAFLD are associated with a reduced risk of T2DM, suggesting that liver-based treatments could reduce the risk of developing T2DM. This review describes the clinical classification of obesity and MAFLD, discusses the clinical features of various types of obesity and MAFLD, emphasizes the role of visceral obesity and insulin resistance (IR) in the development of MAFLD,and summarizes the existing treatments for obesity and MAFLD that reduce the risk of developing T2DM.

The bidirectional relationship between NAFLD and type 2 diabetes: A prospective population-based cohort study

BACKGROUND AND AIMS

To explore the bidirectional relationship between NAFLD and type 2 diabetes and the possible directions of the main effect.

METHODS AND RESULTS

30 633 participants from the Jinchang cohort were enrolled. Firstly, cox proportional hazards regression model was used to assess the unidirectional causality between NAFLD and prediabetes and type 2 diabetes. Secondly, cross-lag path analysis model was conducted to estimate the bidirectional relationship between NAFLD and prediabetes and type 2 diabetes, and to determine the direction of the main effects. Finally, potential effect modifications were also considered by age, sex, hyperlipidemia, and overweight/obesity. We found that NAFLD increased the risk of prediabetes and type 2 diabetes with adjusted HR (95%CI) of 1.355(95%CI: 1.255-1.462) and 1.898(95%CI: 1.415-2.545), respectively. Prediabetes and type 2 diabetes also increased the risk of NAFLD, with adjusted HR (95%CI) of 1.245(95%CI: 1.115-1.392) and 1.592(95%CI: 1.373-1.846), respectively. Cross-lag path analysis showed that NAFLD significantly affected the incidence of prediabetes (β = 0.285, P < 0.001), while the effect on type 2 diabetes was not statistically significant. The effect of prediabetes and type 2 diabetes on the risk of NAFLD was weak, and the path coefficients were 0.076 and 0.037, respectively. Stratified analyses showed similar results.

CONCLUSION

This study provides evidence that there was a bidirectional causal association between NAFLD and type 2 diabetes, and the progression from NAFLD through prediabetes to type 2 diabetes may be the main pathway.

Greater Severity of Steatosis Is Associated with a Higher Risk of Incident Diabetes: A Retrospective Longitudinal Study

BACKGRUOUND

Fatty liver is associated with increased risk of developing type 2 diabetes. We aimed to evaluate whether the severity of hepatic steatosis is associated with incident diabetes.

METHODS

We conducted a longitudinal analysis using data from 1,798 participants who underwent a comprehensive health checkup and abdominal computed tomography (CT). We assessed the association between baseline liver attenuation value on non-contrast CT images and risk of incident diabetes. All the participants were categorized into three groups based on the baseline liver attenuation value on non-contrast CT images: without hepatic steatosis (>57 Hounsfield unit [HU]), mild hepatic steatosis (41-57 HU), and moderate to severe hepatic steatosis (≤40 HU).

RESULTS

During a median follow-up period of 5 years, 6.0% of the study participants progressed to diabetes. The incidence of diabetes was 17.3% in the moderate to severe hepatic steatosis group, 9.0% in the mild steatosis group, and 2.9% in those without hepatic steatosis. In a multivariate adjustment model, as compared with participants without hepatic steatosis, those with moderate to severe steatosis had a hazard ratio (HR) of 3.24 (95% confidence interval [CI], 1.64 to 4.2) for the development of diabetes, and those in the mild steatosis group had a HR of 2.33 (95% CI, 1.42 to 3.80). One standard deviation decrease in mean CT attenuation values of the liver was associated with a 40% increase in the development of diabetes (multivariate adjusted HR, 1.40; 95% CI, 1.2 to 1.63).

CONCLUSION

We found a positive association between severity of hepatic steatosis and risk of incident diabetes. Greater severity of steatosis was associated with a higher risk of incident diabetes.

Relationship between the dynamics of non-alcoholic fatty liver disease and incident diabetes mellitus

The aim of the current study was to evaluate the association between changes in non-alcoholic fatty liver disease (NAFLD) over time and risk of incident diabetes mellitus (DM). In total, 3047 subjects without underlying DM were followed up for 14 years from the Anseong-Ansan cohort. NAFLD status was determined biennially using the hepatic steatosis index (HSI), and subjects were clustered into seven groups according to changes in HSI, body mass index (BMI), and homeostatic model assessment of insulin resistance (HOMA-IR): none, persistent, transient, transient resolved, resolved, incident, and recurrent NAFLD (Groups 1-7, respectively). Predictive abilities were compared between the dynamics of HSI and single time points. Regarding the changes in HSI, the risk of incident DM was highest in Group 2 (hazard ratio [HR] 2.710; P < 0.001), followed by Groups 7 (HR 2.062; P < 0.001) and 3 (HR 1.559; P = 0.027). The predictive ability for DM was powerful in order of HOMA-IR, HSI and BMI. The dynamics of NAFLD were less predictive of incident DM than single time-point NAFLD. In conclusion, NAFLD is more useful than BMI in predicting incident DM. However, NAFLD status at single time points can better predict incident DM than dynamic changes in HSI.

Long-term effects of the changes in hepatic steatosis status on the risk of incident type 2 diabetes mellitus: A 15-year community-based prospective cohort study

AIMS

We investigated the long-term effect of changes in hepatic steatosis on the risk of developing T2DM.

METHODS

We evaluated 3510 participants from the 2001-2016 Korean Genome and Epidemiology Study. Those with significant alcohol consumption or T2DM during 2001-2004 were excluded. Steatosis was defined as non-alcoholic fatty liver disease-liver fat score (NAFLD-LFS) of over -0.64, and baseline values were assessed between 2001 and 2002. Differences in NAFLD-LFS (ΔLFS) and changes in steatosis status (no, intermittent [resolved or incident], and persistent steatosis) were assessed between 2003 and 2004. Changes in the risk of diabetes status were observed until 2016.

RESULTS

Over 52,650 person-years of follow-up, T2DM developed in 296 participants (8.4%). The incidence of diabetes in those with no steatosis, intermittent steatosis, and persistent steatosis during follow-up increased by 5.1%, 14.1%, and 27.1% respectively. Multivariate-adjusted analysis revealed that the risk was higher in those with persistent steatosis than those with no steatosis and intermittent steatosis. Baseline NAFLD-LFS and ΔLFS was associated with increased risk of incident T2DM.

CONCLUSIONS

Initial severity as well as aggravation of steatosis is an independent predictor of incident T2DM. Strategies aimed at reducing liver fat may prevent future development of diabetes among patients with NAFLD.

Non-Alcoholic Fatty Liver Disease and Its Association With Diabetes Mellitus

There is a bidirectional relationship between non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM). The liver has a vital role in the pathophysiology of both diseases as it leads to the development of insulin resistance (IR), which in turn results in NAFLD and T2DM. It has been shown that T2DM increases the risk of NAFLD progression. Furthermore, the presence of NAFLD raises the probability of T2DM complications, which explains the increased rates of NAFLD screening in patients with T2DM. In addition, there are common management options for the two diseases. Lifestyle changes can play a role in the initial management of both diseases. Medications that are used to treat T2DM are also used in the management of NAFLD, such as metformin, thiazolidinediones (TZD), glucagon-like peptide-1 (GLP-1) analogues, and dipeptidyl peptidase-4 (DPP4) inhibitors. Bariatric surgery is often used as a last resort and has shown promising results. Lifestyle interventions with diet and exercise are important postoperatively to maintain the weight loss. There are many novel treatments that are being investigated for the treatment of NAFLD, targeting multiple pathophysiologic pathways. This review aims to shed some light on the intricate relationship between NAFLD and T2DM and how IR links both diseases. We also try to raise awareness among clinicians about this relationship and how the presence of one disease should raise a high index of suspicion for the existence of the other.

The complex link between NAFLD and type 2 diabetes mellitus - mechanisms and treatments

Nonalcoholic fatty liver disease (NAFLD) has reached epidemic proportions worldwide. NAFLD and type 2 diabetes mellitus (T2DM) are known to frequently coexist and act synergistically to increase the risk of adverse (hepatic and extra-hepatic) clinical outcomes. T2DM is also one of the strongest risk factors for the faster progression of NAFLD to nonalcoholic steatohepatitis, advanced fibrosis or cirrhosis. However, the link between NAFLD and T2DM is more complex than previously believed. Strong evidence indicates that NAFLD is associated with an approximate twofold higher risk of developing T2DM, irrespective of obesity and other common metabolic risk factors. This risk parallels the severity of NAFLD, such that patients with more advanced stages of liver fibrosis are at increased risk of incident T2DM. In addition, the improvement or resolution of NAFLD (on ultrasonography) is associated with a reduction of T2DM risk, adding weight to causality and suggesting that liver-focused treatments might reduce the risk of developing T2DM. This Review describes the evidence of an association and causal link between NAFLD and T2DM, discusses the putative pathophysiological mechanisms linking NAFLD to T2DM and summarizes the current pharmacological treatments for NAFLD or T2DM that might benefit or adversely affect the risk of T2DM or NAFLD progression.

The Repeatedly Elevated Fatty Liver Index Is Associated With Increased Mortality: A Population-Based Cohort Study

Aims

Non-alcoholic fatty liver disease (NAFLD) has a dynamic disease course, therefore repeated measurements of NAFLD status could have benefits rather than single one. The aim of this study was to investigate the effects of persistent NAFLD on the incidence of myocardial infarction (MI) and stroke and all-cause mortality by using repeated measurement of fatty liver index (FLI).

Methods

About 3 million subjects who had undergone the health screening four times from 2009 until 2013 were included. NAFLD was defined as an FLI ≥60. FLI points were defined as the number of times participants meeting the criteria of NAFLD (0-4). Outcomes included all-cause mortality, MI, and stroke.

Results

The higher the FLI points, the higher the risk of all-cause mortality, MI, and stroke (P for trend <0.001, all). Subjects with four FLI points had a higher risk of all-cause mortality (aHR, 1.86; 95% CI, 1.75-1.98; P < 0.001), incidence of MI (aHR, 1.3; 95% CI, 1.21-1.40; P < 0.001), and stroke (aHR, 1.27; 95% CI, 1.19-1.37; P < 0.001) after adjustment for age, sex, smoking, alcohol consumption, income, hypertension, dyslipidemia, diabetes, body mass index, and physical activity. When the 1st and the last FLI were compared, the "incident NAFLD" group had a higher risk for death compared to the "no NAFLD" group (aHR, 1.46; 95% CI, 1.37-1.55), and the "regression of NAFLD" group had a decreased risk for death compared to the "persistent NAFLD" group (aHR, 0.83; 95% CI, 0.77-0.89).

Conclusion

Repeated evaluations of NAFLD status based on FLI measurements could help physicians identify higher-risk groups in terms of mortality, MI, and stroke. The association between FLI worsening or improvement and outcomes also suggests clinical benefits of the prevention and treatment of NAFLD.

Human and molecular genetics shed lights on fatty liver disease and diabetes conundrum

The causal role of abdominal overweight/obesity, insulin resistance and type 2 diabetes (T2D) on the risk of fatty liver disease (FLD) has robustly been proven. A consensus of experts has recently proposed the novel definition of 'metabolic dysfunction-associated fatty liver disease, MAFLD' instead of 'nonalcoholic fatty liver disease, NAFLD', emphasizing the central role of dysmetabolism in the disease pathogenesis. Conversely, a direct and independent contribution of FLD per se on risk of developing T2D is still a controversial topic. When dealing with FLD as a potential risk factor for T2D, it is straightforward to think of hepatic insulin resistance as the most relevant underlying mechanism. Emerging evidence supports genetic determinants of FLD (eg PNPLA3, TM6SF2, MBOAT7, GCKR, HSD17B13) as determinants of insulin resistance and T2D. However, recent studies highlighted that the key molecular mechanism of dysmetabolism is not fat accumulation per se but the degree of hepatic fibrosis (excess liver fat content-lipotoxicity), leading to reduced insulin clearance, insulin resistance and T2D. A consequence of these findings is that drugs that will ameliorate liver fat accumulation and fibrosis in principle may also exert a beneficial effect on insulin resistance and risk of T2D in individuals with FLD. Finally, initial findings show that these genetic factors might be directly implicated in modulating pancreatic beta-cell function, although future studies are needed to fully understand this relationship.

Nonalcoholic Fatty Liver Disease and Diabetes: An Epidemiological Perspective

Nonalcoholic fatty liver disease (NAFLD) is thought to stem from the body's inability to store excess energy in adipocytes; as such, it is commonly viewed as the hepatic manifestation of metabolic syndrome. The pathogenesis of NAFLD involves ectopic fat accumulation, which also takes place in the liver, muscle and visceral fat. NAFLD is rapidly becoming more widespread in Korea, with an estimated prevalence of 30% in adults. Type 2 diabetes mellitus (T2DM) and NAFLD share insulin resistance as a common pathophysiological mechanism, and each of these two diseases affects the development of the other. Recent studies have suggested that NAFLD is often present as a comorbidity in T2DM patients. The mutual interrelationship between these conditions is shown by findings suggesting that T2DM can exacerbate NAFLD by promoting progression to nonalcoholic hepatosteatosis or fibrosis, while NAFLD causes the natural course of diabetic complications to worsen in T2DM patients. It remains unknown whether one disease is the cause of the other or vice versa. In this review, I would like to discuss current epidemiological data on the associations between NAFLD and T2DM, and how each disease affects the course of the other.

Gut Microbiota and Risk of Persistent Nonalcoholic Fatty Liver Diseases

Gut dysbiosis is regarded as a pathogenetic factor of nonalcoholic fatty liver disease (NAFLD), but its role in NAFLD persistence is unknown. We investigated the influence of the gut microbiota on persistent NAFLD. This cohort study included 766 subjects with 16S ribosomal RNA (rRNA) gene sequencing data from fecal samples at baseline who underwent repeated health check-up examinations. Fatty liver was determined using ultrasound at baseline and follow-up. Participants were categorized into four groups: none (control), developed, regressed, or persistent NAFLD. The persistent NAFLD group had lower richness compared with the control group. Significant differences were also found in both non-phylogenic and phylogenic beta diversity measures according to NAFLD persistence. Pairwise comparisons indicated that taxa abundance mainly differed between the control and persistent NAFLD groups. A relative high abundance of Fusobacteria and low abundance of genera Oscillospira and Ruminococcus of the family Ruminococcaceae and genus Coprococcus of the family Lachnospiraceae were found in the persistent NAFLD group. Based on the functional predictions, pathways related to primary and secondary bile acid biosynthesis were highly detected in the persistent NAFLD group compared with the control group. These findings support that the composition of the gut microbiome associated with dysregulation of bile acid biosynthetic pathways may contribute to the persistence of NAFLD. This is the first cohort study to demonstrate the influence of microbiota on persistent NAFLD. Our findings may help identify potential targets for therapeutic intervention in NAFLD.

Nonalcoholic Fatty Liver Disease in Diabetes. Part I: Epidemiology and Diagnosis

Nonalcoholic fatty liver disease (NAFLD) and diabetes are common metabolic disorders whose prevalence rates are expected to rise worldwide, corresponding to aging and increasingly obese populations. Compared to the general population (around 25%), 50% to 70% of people with diabetes have NAFLD, and NAFLD severity (including fibrosis) tends to be worsened by the presence of diabetes. NAFLD is considered an emerging risk factor for type 2 diabetes mellitus and a contributor to the development of chronic diabetes-related complications. This reciprocal relationship demonstrates the importance of confirming suspected NAFLD in patients with diabetes. Due to the invasive nature of liver biopsy to assess NAFLD status, various alternative non-invasive modalities have been developed and validated. Here, we summarized the epidemiology of NAFLD in patients with diabetes and reviewed currently available imaging modalities and biomarker-based prediction models for their ability to detect liver steatosis and/or fibrosis.

Hypothyroidism and nonalcoholic fatty liver disease - a chance association?

Background Nonalcoholic fatty liver disease (NAFLD) defines the clinical-pathological spectrum of hepatic lipotoxicity, which may progress to hepatic fibrosis and its complications. Thyroid hormone is a master regulator of cell metabolism and body fat distribution. Whether hypothyroidism is associated or not with an increased risk of developing NAFLD and its fibrotic progression is both clinically and physiopathologically relevant. Indeed, answering this research question would carry major pathogenic and therapeutic implications. Method PubMed database was searched using relevant key-words such as hypothyroidism; NAFLD; nonalcoholic steatohepatitis; cirrhosis; hepatocellular carcinoma; epidemiology; pathogenesis; natural history. The epidemiological studies and the meta-analyses published so far were identified as well as those studies addressing the physiopathology underlying this association. Results Many observational studies have investigated the association between either subclinical or overt hypothyroidism and NAFLD. Data are conflicting: some original and meta-analytical studies demonstrated that hypothyroidism, (mainly subclinical hypothyroidism), was common, occurring in approximately 25% of individuals with imaging-defined or biopsy-proven NAFLD; other studies, however, failed to identify a significant association between hypothyroidism and NAFLD. Moreover, such an association is biologically plausible based on the specific physiopathological impact of thyroid hormone and thyroid stimulating hormone (TSH) on metabolism of hepatocytes and accumulation and distribution of body fat. Conclusions The findings from the present review support a significant association between primary hypothyroidism and risk of development and progression of NAFLD. However, further studies evaluating the relative importance of subclinical versus overt hypothyroidism as well as addressing the mechanisms underlying the association of hypothyroidism with NAFLD are eagerly awaited.