Twenty-five-year trajectories of insulin resistance and pancreatic β-cell response and diabetes risk in nonalcoholic fatty liver disease

Inter-organ metabolic interaction networks in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a multisystem metabolic disorder, marked by abnormal lipid accumulation and intricate inter-organ interactions, which contribute to systemic metabolic imbalances. NAFLD may progress through several stages, including simple steatosis (NAFL), non-alcoholic steatohepatitis (NASH), cirrhosis, and potentially liver cancer. This disease is closely associated with metabolic disorders driven by overnutrition, with key pathological processes including lipid dysregulation, impaired lipid autophagy, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and local inflammation. While hepatic lipid metabolism in NAFLD is well-documented, further research into inter-organ communication mechanisms is crucial for a deeper understanding of NAFLD progression. This review delves into intrahepatic networks and tissue-specific signaling mediators involved in NAFLD pathogenesis, emphasizing their impact on distal organs.

Hepatic Fat in Participants With and Without Incident Diabetes in the Diabetes Prevention Program Outcome Study

CONTEXT

There is little information about fatty liver in prediabetes as it transitions to early diabetes.

OBJECTIVE

This study is aimed at evaluating the prevalence and determinants of fatty liver in the Diabetes Prevention Program (DPP).

METHODS

We measured liver fat as liver attenuation (LA) in Hounsfield units (HU) in 1876 participants at ~14 years following randomization into the DPP, which tested the effects of lifestyle or metformin interventions versus standard care to prevent diabetes. LA was compared among intervention groups and in those with versus without diabetes, and associations with baseline and follow-up measurements of anthropometric and metabolic covariates were assessed.

RESULTS

There were no differences in liver fat between treatment groups at 14 years of follow-up. Participants with diabetes had lower LA (mean ± SD: 46 ± 16 vs 51 ± 14 HU; P < 0.001) and a greater prevalence of fatty liver (LA < 40 HU) (34% vs 17%; P < 0.001). Severity of metabolic abnormalities at the time of LA evaluation was associated with lower LA categories in a graded manner and more strongly in those with diabetes. Averaged annual fasting insulin (an index of insulin resistance [OR, 95% CI 1.76, 1.41-2.20]) waist circumference (1.63, 1.17-2.26), and triglyceride (1.42, 1.13-1.78), but not glucose, were independently associated with LA < 40 HU prevalence.

CONCLUSION

Fatty liver is common in the early phases of diabetes development. The association of LA with insulin resistance, waist circumference, and triglyceride levels emphasizes the importance of these markers for hepatic steatosis in this population and that assessment of hepatic fat in early diabetes development is warranted.

Nonalcoholic fatty liver disease increases the risk of diabetes in young adults: A nationwide population-based study in Korea

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of diabetes but has been rarely investigated in young adults. In this study, we investigated the relationship between NAFLD and incident diabetes risk in young adults using nationwide Korean population data.

METHODS

This population-based cohort study from the Korean National Health Insurance Service included adults aged 20 through 39 years who underwent a health examination from 2009 to 2012. NAFLD was defined as a fatty liver index (FLI) ≥60 in the absence of alcohol consumption of ≥30 g/day. Newly diagnosed diabetes during follow-up was identified using claims data. Cox regression was used to calculate the hazard ratio for incident diabetes after adjusting for classical confounders.

FINDINGS

Among the 5,254,786 participants, 9.3% had an FLI ≥60. During the median follow-up of 8.6 years, 91,885 cases of incident diabetes occurred. In multivariable analysis, the risk of incident diabetes was significantly higher in the NAFLD group than the control group (adjusted hazard ratio = 4.97, 95% confidence interval, 4.90-5.05). Stratified analyses showed higher associations in those who were ≥30 years, male, obese, smokers, alcohol consumers, and did not regularly exercise (all P < 0.001).

CONCLUSIONS

NAFLD is associated with a five-fold increased risk of incident diabetes in young adults. These results suggest an independent high risk for incident diabetes in young adults and underscore the importance of paying early attention to patients who develop NAFLD before middle age.

Non-alcoholic fatty liver disease and risk of incident diabetes mellitus: an updated meta-analysis of 501 022 adult individuals

OBJECTIVE

Follow-up studies have shown that non-alcoholic fatty liver disease (NAFLD) is associated with an increased risk of incident diabetes, but currently, it is uncertain whether this risk changes with increasing severity of NAFLD. We performed a meta-analysis of relevant studies to quantify the magnitude of the association between NAFLD and risk of incident diabetes.

DESIGN

We systematically searched PubMed, Scopus and Web of Science databases from January 2000 to June 2020 using predefined keywords to identify observational studies with a follow-up duration of at least 1 year, in which NAFLD was diagnosed by imaging techniques or biopsy. Meta-analysis was performed using random-effects modelling.

RESULTS

33 studies with 501 022 individuals (30.8% with NAFLD) and 27 953 cases of incident diabetes over a median of 5 years (IQR: 4.0-19 years) were included. Patients with NAFLD had a higher risk of incident diabetes than those without NAFLD (n=26 studies; random-effects HR 2.19, 95% CI 1.93 to 2.48; I2 =91.2%). Patients with more 'severe' NAFLD were also more likely to develop incident diabetes (n=9 studies; random-effects HR 2.69, 95% CI 2.08 to 3.49; I2 =69%). This risk markedly increased across the severity of liver fibrosis (n=5 studies; random-effects HR 3.42, 95% CI 2.29 to 5.11; I2=44.6%). All risks were independent of age, sex, adiposity measures and other common metabolic risk factors. Sensitivity analyses did not alter these findings. Funnel plots did not reveal any significant publication bias.

CONCLUSION

This updated meta-analysis shows that NAFLD is associated with a ~2.2-fold increased risk of incident diabetes. This risk parallels the underlying severity of NAFLD.

Distinct Dose-Dependent Association of Free Fatty Acids with Diabetes Development in Nonalcoholic Fatty Liver Disease Patients

BACKGROUND

Excessive delivery of free fatty acids (FFAs) to the liver promotes steatosis and insulin resistance (IR), with IR defined as reduced glucose uptake, glycogen synthesis and anti-lipolysis stimulated by normal insulin levels. Whether the associations between FFAs and diabetes development differ between patients with and without nonalcoholic fatty liver disease (NAFLD) remains unclear.

METHODS

Consecutive subjects (2,220 NAFLD subjects and 1,790 non-NAFLD subjects according to ultrasound imaging) were enrolled from the First Affiliated Hospital of Sun Yat-sen University between 2009 and 2019. The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated.

RESULTS

There was an approximate J-shaped relationship between FFA levels and HOMA-IR in the NAFLD group. Higher FFA concentration quartiles were associated with higher risks of IR (odds ratio [OR], 9.24; 95% confidence interval [CI], 6.43 to 13.36), prediabetes (OR, 10.48; 95% CI, 5.66 to 19.39), and type 2 diabetes mellitus (T2DM; OR, 19.43; 95% CI, 12.75 to 29.81) in the NAFLD group but not in the non-NAFLD group. The cut-off points for the FFA levels increased in a stepwise manner in discriminating IR, prediabetes and T2DM (573, 697, and 715 μmol/L) in the NAFLD group but not in non-NAFLD individuals.

CONCLUSION

A distinct dose-dependent relationship of FFA levels was found with IR, prediabetes and T2DM in NAFLD patients. Screening serum FFA levels in NAFLD patients would be valuable in preventing diabetes development.

Therapy for Nonalcoholic Fatty Liver Disease: Current Options and Future Directions

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent chronic liver disease that is driven by the metabolic syndrome. NAFLD encompasses nonalcoholic fatty liver, >5% fat in the liver without inflammation of fibrosis, nonalcoholic steatohepatitis (NASH), fat plus varying degrees of inflammation and fibrosis, and cirrhosis of the liver from NASH. As facets of the metabolic syndrome, particularly diabetes and obesity, become more common worldwide, the incidence of new NAFLD is increasing.

METHODS

A qualitative systematic review was performed via searches of PubMed and ClinicalTrials.gov for therapeutic interventions for NAFLD.

FINDINGS

Current therapies rely on metabolic syndrome risk factor control and lifestyle changes to achieve weight loss. Because sustained weight loss is difficult for many patients, there is a critical unmet need for pharmacotherapy to treat NAFLD, especially the progressive form, NASH, to prevent cirrhosis of the liver. New therapies for NAFLD focus on the subset of patients with NASH and some degree of fibrosis. Novel mechanisms of action, including farnesoid X nuclear receptor agonism, C-C motif chemokine receptor 2 and receptor 5 antagonism, stearoyl-CoA desaturase-1, and thyroid hormone receptor β agonism, are currently under investigation as monotherapy. The products also hold potential for use in combination with and without insulin sensitizers and other established drugs in the future.

IMPLICATIONS

This review of NASH treatments details the interventions that are currently available as well as those in late-stage clinical trials that may represent the future of NASH therapy.

Association between plasminogen activator inhibitor-1 in young adulthood and nonalcoholic fatty liver disease in midlife: CARDIA

BACKGROUND

Prior studies have demonstrated a cross-sectional association between elevated plasminogen activator inhibitor-1 (PAI-1) levels and nonalcoholic fatty liver disease (NAFLD). However, there are no prospective longitudinal assessments of the association between PAI-1 and NAFLD. We aimed to describe the association between PAI-1 levels in early adulthood with NAFLD in midlife.

METHODS

Among the 5115 participants in the coronary artery risk development in young adults (CARDIA) study, participants were randomly selected from a subset that was free of obesity, diabetes and hypertension at the 1992-1993 exam and attended the 2005-2006 exam (n = 996). A subset of participants (n = 896) also had CT liver fat measured (2010-2011). Participants with secondary causes of steatosis were excluded (n = 87). NAFLD was defined as liver attenuation ≤51 Hounsfield units. Logistic regression models assessed the association between PAI-1 and NAFLD.

RESULTS

Of 809 participants, 53% were female, 37% black with a mean age of 32 years. Median PAI-1 level at 1st assessment (1992-1993) was 23.4 ng/mL among participants with NAFLD vs 11.9 ng/mL among those without NAFLD (P < .0001). Median PAI-1 level at 2nd assessment (2005-2006) was 55.6 ng/mL among participants with NAFLD vs 19.5 ng/mL among those without NAFLD (P < .0001). Higher PAI-1 levels were independently associated with NAFLD (1st assessment adjusted OR [AOR] 2.16 per 1 standard deviation higher log(PAI-1) level (95% confidence interval [CI] 1.63-2.85); 2nd assessment AOR 2.71 (95% CI 2.03-3.61)).

CONCLUSIONS

Plasma PAI-1 levels in young adulthood were independently associated with NAFLD in midlife. Further studies may indicate whether PAI-1 plays a role in NAFLD pathophysiology.

Pancreas fat quantification with quantitative CT: an MRI correlation analysis

AIM

To assess the fat content of the pancreas using quantitative computed tomography (QCT) and to correlate the results with chemical-shift-encoded magnetic resonance imaging (CSE-MRI) measurements of proton density fat fraction (PDFF).

MATERIAL AND METHODS

Institutional review board approval for this research was obtained and 52 participants (25 men, 27 women; mean age 35.1 years; age range 22-50 years), who were enrolled in the Prospective Urban Rural Epidemiology (PURE) Study, underwent QCT and CSE-MRI for quantification of fat content in the pancreas. Two observers placed regions of interest (area of 100-130 mm²) in the head, body, and tail of the pancreas as closely matched as possible on the two scans. Pearson correlation and Bland-Altman analysis were performed to evaluate the correlation between the QCT and CSE-MRI measurements and the systematic difference between the two techniques.

RESULTS

The QCT and CSE-MRI measurements of pancreatic fat content were well correlated (r=0.805, p<0.0001), although Bland-Altman analysis showed that the QCT measurements were systematically lower by 6.3% compared to CSE-MRI PDFF.

CONCLUSION

In conclusion, the results of this study suggest good correlation between QCT and CSE-MRI measurements of pancreatic fat content. Further studies are required to improve the numerical agreement of QCT measurements with PDFF.

Elevated TPOAb is a Strong Predictor of Autoimmune Development in Patients of Type 2 Diabetes Mellitus and Non-Alcoholic Fatty Liver Disease: A Case-Control Study

OBJECTIVE

The aim of this study was to assess the prevalence of thyroid autoimmunity in T2DM with NAFLD, furthermore explore the relationship between elevated TPOAb titer and the severity of NAFLD.

METHODS

A total of 400 patients with T2DM were divided into two groups according to NAFLD. Thyroid function and other metabolic indicators were measured.

RESULTS

There were more TPOAb-positive patients in both groups, and the prevalence of TPOAb positive was significantly different in two groups (17% vs 6.9%, p< 0.01). FT4 was significantly lower in patients with T2DM with NAFLD (median FT4 0.89 vs 1.08, p < 0.001), while TSH was increased (median TSH 2.85 vs 2.28, p < 0.05). In patients with T2DM with NAFLD, the proportion of women in the thyroid autoimmune-positive group was significantly higher than the negative (71.1% vs 46%, p < 0.01). Similarly, thyroid autoimmune-positive T2DM and NAFLD patients had lower FT4 levels (median FT4 0.59 vs 0.92, p < 0.001), higher TSH levels (median TSH 3.65 vs 2.67, p < 0.001), and much higher TPOAb/TGAb (median TPOAb/TGAb 6.8 vs 1.46, p < 0.001). The increase of TPOAb was significantly correlated with the severity of fatty liver. HbA1c, TC, TG, TSH, TPOAb/TGAb and severity of fatty liver were risk factors of thyroid autoimmunity.

CONCLUSION

Autoimmune thyroid disease is more common in patients with T2DM complicated with NAFLD. Elevated TPOAb titer is closely related to fatty liver, suggesting that elevated TPOAb titer is a predictor of autoimmune development in T2DM with NAFLD.

Fasting glucose and insulin resistance trajectories during young adulthood and mid-life cardiac structure and function

AIMS

We assessed whether fasting glucose (FG) and insulin resistance (IR) trajectories during young adulthood are associated with changes in cardiac structure and function.

METHODS

We used data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study (baseline: 1985-1986). Echocardiography was performed after 25 (Y25) and 30 years of follow-up. Group-based modeling was used to determine 25-year trajectories in FG and IR. We assessed differences at Y25 and 5-year longitudinal change in cardiac structure and function after adjustment for demographics, cumulative exposure to traditional cardiovascular risk factors, and baseline FG or IR.

RESULTS

We identified five FG trajectory groups among 2414 individuals and three IR trajectory groups among 2358 individuals. Moderate-increasing FG trajectory was associated with lower lateral E' velocity (difference: -0.9 cm/s, 95%CI: -0.3, -1.5) and with greater left ventricular (LV) mass index (difference: 2.7 g/m2.7, 95%CI: 0.7, 4.7) at Y30 compared to low-stable FG. High-increasing IR trajectory was associated with lower lateral E' velocity and septal E' velocity at Y30 compared to low-decreasing IR trajectory.

CONCLUSIONS

Trajectories in FG and IR over 25 years before the development of diabetes are associated with unfavorable differences in LV structure and diastolic function beyond single values of FG and IR.

Blood concentrations of lipopolysaccharide-binding protein, high-sensitivity C-reactive protein, tumor necrosis factor-α, and Interleukin-6 in relation to insulin resistance in young adolescents

BACKGROUND

We assessed the association of insulin resistance as indicated by the homeostatic model assessment of insulin resistance (HOMA-IR) with inflammatory molecules, lipopolysaccharide-binding protein (LBP), high sensitivity C-reactive protein (hs-CRP), Tumor necrosis factor-α (TNF-α), and Interleukin-6 (IL-6) in urban young adolescents.

METHODS

Seventy-six adolescents (36 subjects with HOMA-IR ≥ 2.6 and 40 subjects with HOMA-IR < 2.6) were included in the study. We assessed anthropometric and laboratory measures, such as BMI, blood pressure, insulin sensitivity, liver enzymes, and lipid profiles along with the aforementioned inflammatory biomarkers. The diagnostic accuracy of LBP, hs-CRP, TNF-α, and IL-6 for insulin resistance was evaluated by using the receiver operating characteristic (ROC) curve analysis.

RESULTS

The mean age of the study subjects was 12.0 [12.0-13.0] y. Circulating LBP plasma concentration and hs-CRP were significantly increased in subjects with HOMA-IR ≥ 2.6 when compared with those with HOMA-IR < 2.6 (P < .0001). There was no difference in TNF-α or IL-6 concentrations between groups. Comparisons based on the area under the ROC curve for LBP, hs-CRP, TNF-α, and IL-6 with regard to insulin resistance (HOMA-IR ≥ 2.6) were 0.8384 (95% CI: 0.7380 to 0.9388), 0.7907 (95% CI: 0.6701 to 0.9113), 0.6207 (95% CI: 0.4770 to 0.7643), and 0.5763 (95% CI: 0.4285 to 0.7241), respectively.

CONCLUSIONS

Among LBP, hs-CRP, TNF-α, and IL-6, plasma LBP has the greatest diagnostic accuracy for insulin resistance in young adolescents. Prospective studies are warranted to delineate the value of LBP in the prediction of insulin resistance.