NAFLD improves risk prediction of type 2 diabetes: with effect modification by sex and menopausal status

Epidemiology, screening, and co-management of type 2 diabetes mellitus and metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as NAFLD, is increasingly recognized as a prevalent global burden. Type 2 diabetes mellitus (T2DM), another important metabolic disease, is considered a major contributor to the development of MASLD. MASLD and T2DM have a strong association with each other due to shared pathogenic mechanisms. The co-existence of the 2 diseases increases the risk of liver-related adverse outcomes and imposes a heavier burden on extrahepatic outcomes, representing a substantial public health issue. Effective assessment and management of T2DM combined with MASLD necessitate a multidisciplinary approach. The emergence of numerous RCTs has shed light on the treatment of T2DM combined with MASLD. This review uncovers the epidemiology of the intertwined T2DM and MASLD, offers insights into the evaluation of hepatic fibrosis in patients with T2DM, glucose monitoring in the MASLD population, and provides comprehensive co-management strategies for addressing both diseases.

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.

Longitudinal Outcomes Associated With Metabolic Dysfunction-Associated Steatotic Liver Disease: A Meta-analysis of 129 Studies

BACKGROUND & AIMS

The progression of metabolic dysfunction-associated steatotic liver disease (MASLD) has been found to manifest in a series of hepatic and extrahepatic complications. A comprehensive meta-analysis of the longitudinal outcomes associated with MASLD has yet to be conducted.

METHODS

To investigate the longitudinal outcomes associated with MASLD, Medline and Embase databases were searched to identify original studies that evaluated the longitudinal risks of incident clinical outcomes among MASLD patients compared with non-MASLD individuals. DerSimonian Laird random-effects meta-analysis was performed. Pooled effect estimates were calculated, and heterogeneity among studies was evaluated.

RESULTS

One hundred twenty-nine studies were included in the meta-analysis. Meta-analysis revealed a significant increase in the risk of cardiovascular outcomes (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.27-1.60; P < .01), various metabolic outcomes such as incident hypertension (HR, 1.75; 95% CI, 1.46-2.08; P < .01), diabetes (HR, 2.56; 95% CI, 2.10-3.13; P < .01), pre-diabetes (HR, 1.69; 95% CI, 1.22-2.35; P < .01), metabolic syndrome (HR, 2.57; 95% CI, 1.13-5.85; P = .02), chronic kidney disease (HR, 1.38; 95% CI, 1.27-1.50; P < .01), as well as all cancers (HR, 1.54; 95% CI, 1.35-1.76; P < .01) among MASLD patients compared with non-MASLD individuals. By subgroup analysis, MASLD patients with advanced liver disease (HR, 3.60; 95% CI, 2.10-6.18; P < .01) were also found to be associated with a significantly greater risk (P = .02) of incident diabetes than those with less severe MASLD (HR, 1.63; 95% CI, 1.0-2.45; P = .02) when compared with non-MASLD.

CONCLUSIONS

The present study emphasizes the association between MASLD and its clinical outcomes including cardiovascular, metabolic, oncologic, and other outcomes. The multisystemic nature of MASLD found in this analysis requires treatment targets to reduce systemic events and end organ complications.

Current status and future trends of the global burden of MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as the most common chronic liver disease globally, affecting more than a third of the world's adult population. This comprehensive narrative review summarizes the global incidence and prevalence rates of MASLD and its related adverse hepatic and extrahepatic outcomes. We also discuss the substantial economic burden of MASLD on healthcare systems, thus further highlighting the urgent need for global efforts to tackle this common and burdensome liver condition. We emphasize the clinical relevance of early interventions and a holistic approach that includes public health strategies to reduce the global impact of MASLD.

Pharmacological Approaches to Nonalcoholic Fatty Liver Disease: Current and Future Therapies

Nonalcoholic fatty liver disease (NAFLD) and its more severe form, nonalcoholic steatohepatitis (NASH), can promote the development of cirrhosis, hepatocellular carcinoma, cardiovascular disease, and type 2 diabetes. Similarly, type 2 diabetes confers the greatest risk for the development of NASH, especially when associated with obesity. Although lifestyle changes are critical to success, early implementation of pharmacological treatments for obesity and type 2 diabetes are essential to treat NASH and avoid disease progression. This article reviews current guidance regarding the use of pharmacological agents such as pioglitazone, glucagon-like peptide 1 receptor agonists, and sodium-glucose cotransporter 2 inhibitors in the setting of NAFLD and NASH. It also reviews the latest information on new drugs currently being investigated for the treatment of NASH.

Nonalcoholic fatty liver disease without overlapping metabolic-associated fatty liver disease and the risk of incident type 2 diabetes

BACKGROUND AND AIMS

Re-classifying NAFLD as metabolic-associated fatty liver (MAFLD) has been proposed. While some people fulfil criteria for NAFLD, they do not have MAFLD; and whether NAFLD-only subjects have increased the risk of type 2 diabetes remains unknown. We compared risk of incident T2D in individuals with: (a) NAFLD-only; and (b) MAFLD, to individuals without fatty liver, considering effect modification by sex.

METHODS

246 424 Koreans without diabetes or a secondary cause of ultrasound-diagnosed hepatic steatosis were studied. Subjects were stratified into: (a) NAFLD-only status and (b) NAFLD that overlapped with MAFLD (MAFLD). Cox proportional hazards models with incident T2D as the outcome were used to estimate hazard ratios (HRs) for: (a) and (b). Models were adjusted for time-dependent covariates, and effect modification by sex was analysed in subgroups.

RESULTS

A total of 5439 participants had NAFLD-only status and 56 839 met MAFLD criteria. During a median follow-up of 5.5 years, 8402 incident cases of T2D occurred. Multivariable-adjusted HRs (95% CI) for incident T2D comparing NAFLD-only and MAFLD to the reference (neither condition) were 2.39 (1.63-3.51) and 5.75 (5.17-6.36) (women), and 1.53 (1.25-1.88) and 2.60 (2.44-2.76) (men), respectively. The increased risk of T2D in the NAFLD-only group was higher in women than in men (p for interaction by sex <0.001) and consistently observed across all subgroups. Risk of T2D was increased in lean participants regardless of metabolic dysregulation (including prediabetes).

CONCLUSIONS

NAFLD-only participants without metabolic dysregulation and the criteria for MAFLD are at increased risk of developing T2D. This association was consistently stronger in women than in men.

Synergistic effect of non-alcoholic fatty liver disease and history of gestational diabetes to increase risk of type 2 diabetes

Whether non-alcoholic fatty liver disease (NAFLD) improves risk prediction for subsequent type 2 diabetes mellitus (T2DM) in women with prior gestational diabetes mellitus (pGDM) is uncertain. We examined the combined effects of NAFLD and pGDM on risk prediction for incident T2DM. This retrospective cohort study included 97,347 Korean parous women without diabetes mellitus at baseline whose mean (SD) age was 39.0 (7.8) years. Cox proportional hazards models were used to estimate hazard ratios (HRs) for incident T2DM according to self-reported pGDM and ultrasound-diagnosed NAFLD at baseline. When combined with conventional diabetes risk factors, the incremental predictive ability of NAFLD and pGDM to identify incident T2DM was assessed. During a median follow-up of 3.9 years, 1,515 cases of incident T2DM occurred. Multivariable-adjusted HRs (95% confidence intervals [CIs]) for incident T2DM comparing pGDM alone, NAFLD alone, and both NAFLD and pGDM to the reference (neither NAFLD nor pGDM) were 2.61 (2.06-3.31), 2.26 (1.96-2.59), and 6.45 (5.19-8.00), respectively (relative excess risk of interaction = 2.58 [95% CI, 1.21-3.95]). These associations were maintained after adjusting for insulin resistance, body mass index, and other potential confounders as time-dependent covariates. The combination of NAFLD and pGDM improved risk prediction for incident T2DM (based on Harrell's C-index, also known as the concordance index, and net reclassification improvement) compared to conventional diabetes risk factors. In conclusion, NAFLD synergistically increases the risk of subsequent T2DM in women with pGDM. The combination of NAFLD and pGDM improves risk prediction for T2DM.

Nonalcoholic fatty liver disease and risk of incident young-onset hypertension: Effect modification by sex

BACKGROUND AND AIMS

Although nonalcoholic fatty liver disease (NAFLD) and hypertension are increasingly common among young adults, it is uncertain if NAFLD affects incidence of young-onset hypertension, and if the association is modified by sex. We investigated potential effect modification by sex on the association between NAFLD and incident hypertension in young adults (<40 years).

METHOD AND RESULTS

This cohort study comprised 85,789 women and 67,553 men aged <40 years without hypertension at baseline. Hepatic steatosis was assessed by liver ultrasound and classified as mild or moderate/severe. Hypertension was defined as blood pressure (BP) ≥130/80 mmHg; self-reported history of physician-diagnosed hypertension; or current use of BP-lowering medications. Cox proportional hazard models were used to estimate hazard ratios (HRs; 95% confidence intervals [CIs]) for incident hypertension by NAFLD status (median follow-up 4.5 years). A total of 25,891 participants developed incident hypertension (incidence rates per 10³ person-years: 15.6 for women and 63.5 for men). Multivariable-adjusted HRs (95% CIs) for incident hypertension comparing no NAFLD (reference) with mild or moderate/severe NAFLD were 1.68 (1.56-1.80) and 1.83 (1.60-2.09) for women and 1.21 (1.17-1.25) and 1.23 (1.17-1.30) for men, respectively. Stronger associations were consistently observed between NAFLD and incident hypertension in women, regardless of obesity/central obesity (all p-values for interaction by sex <0.001).

CONCLUSIONS

NAFLD is a potential risk factor for young-onset hypertension with a relatively greater impact in women and in those with more severe hepatic steatosis.

Non-Alcoholic Fatty Liver Disease or Type 2 Diabetes Mellitus—The Chicken or the Egg Dilemma

In clinical practice, we often deal with patients who suffer from non-alcoholic fatty liver disease (NAFLD) concurrent with type 2 diabetes mellitus (T2DM). The etiopathogenesis of NAFLD is mainly connected with insulin resistance (IR) and obesity. Similarly, the latter patients are in the process of developing T2DM. However, the mechanisms of NAFLD and T2DM coexistence have not been fully elucidated. Considering that both diseases and their complications are of epidemic proportions and significantly affect the length and quality of life, we aimed to answer which of these diseases appears first and thereby highlight the need for their diagnosis and treatment. To address this question, we present and discuss the epidemiological data, diagnoses, complications and pathomechanisms of these two coexisting metabolic diseases. This question is difficult to answer due to the lack of a uniform procedure for NAFLD diagnosis and the asymptomatic nature of both diseases, especially at their beginning stages. To conclude, most researchers suggest that NAFLD appears as the first disease and starts the sequence of circumstances leading ultimately to the development of T2DM. However, there are also data suggesting that T2DM develops before NAFLD. Despite the fact that we cannot definitively answer this question, it is very important to bring the attention of clinicians and researchers to the coexistence of NAFLD and T2DM in order to prevent their consequences.

Sex differences in type 2 diabetes

The prevalence of type 2 diabetes mellitus is increasing in both sexes, but men are usually diagnosed at a younger age and lower body fat mass than women. Worldwide, an estimated 17.7 million more men than women have diabetes mellitus. Women appear to bear a greater risk factor burden at the time of their type 2 diabetes diagnosis, especially obesity. Moreover, psychosocial stress might play a more prominent role in diabetes risk in women. Across their lifespan, women experience greater hormone fluctuations and body changes due to reproductive factors than men. Pregnancies can unmask pre-existing metabolic abnormalities, resulting in the diagnosis of gestational diabetes, which appears to be the most prominent risk factor for progression to type 2 diabetes in women. Additionally, menopause increases women's cardiometabolic risk profile. Due to the progressive rise in obesity, there is a global increase in women with pregestational type 2 diabetes, often with inadequate preconceptual care. There are differences between men and women regarding type 2 diabetes and other cardiovascular risk factors with respect to comorbidities, the manifestation of complications and the initiation of and adherence to therapy. Women with type 2 diabetes show greater relative risk of CVD and mortality than men. Moreover, young women with type 2 diabetes are currently less likely than men to receive the treatment and CVD risk reduction recommended by guidelines. Current medical recommendations do not provide information on sex-specific or gender-sensitive prevention strategies and management. Thus, more research on sex differences, including the underlying mechanisms, is necessary to increase the evidence in the future. Nonetheless, intensified efforts to screen for glucose metabolism disorders and other cardiovascular risk factors, as well as the early establishment of prophylactic measures and aggressive risk management strategies, are still required for both men and women at increased risk of type 2 diabetes. In this narrative review we aim to summarise sex-specific clinical features and differences between women and men with type 2 diabetes into risk factors, screening, diagnosis, complications and treatment.

Banting memorial lecture 2022: 'Type 2 diabetes and nonalcoholic fatty liver disease: Partners in crime'

Nonalcoholic fatty liver disease (NAFLD) was first described in the 1980s, but in the 21st century, NAFLD has become a very common condition. The explanation for this relatively recent problem is in large part due to the recent epidemic of obesity and type 2 diabetes (T2DM) increasing the risk of NAFLD. NAFLD is a silent condition that may not become manifest until severe liver damage (fibrosis or cirrhosis) has occurred. Consequently, NAFLD and its complications often remain undiagnosed. Research evidence shows that NAFLD is extremely common and some estimates suggest that it occurs in up to 70% of people with T2DM. In the last 5 years, it has become evident that NAFLD not only increases the risk of cirrhosis, primary liver cancer and end-stage liver disease, but NAFLD is also an important multisystem disease that has major implications beyond the liver. NAFLD increases the risk of incident T2DM, cardiovascular disease, chronic kidney disease and certain extra-hepatic cancers, and NAFLD and T2DM form part of a vicious spiral of worsening diseases, where one condition affects the other and vice versa. Diabetes markedly increases the risk of liver fibrosis and liver fibrosis is the most important risk factor for hepatocellular carcinoma. It is now possible to diagnose liver fibrosis with non-invasive tools and therefore it is important to have clear care pathways for the management of NAFLD in patients with T2DM. This review summarises key recent research that was discussed as part of the Banting lecture at the annual scientific conference in 2022.