Nonalcoholic Fatty Liver Disease and Abdominal Fat Accumulation According to Vitamin D Status in Patients with Type 2 Diabetes

Relationship between Non-Alcoholic Fatty Liver Disease and Visceral Fat Measured by Imaging-Based Body Composition Analysis: A Systematic Review

Imaging-based body composition analysis can quantify visceral fat, which is an important feature of lean non-alcoholic fatty liver disease (NAFLD) patients. This review assesses current evidence of the relationship between NAFLD, particularly hepatic steatosis, and visceral fat that is measured using imaging-based body composition analysis. PubMed Central and ScienceDirect were searched for studies that provided quantification of the relationship between NAFLD, hepatic steatosis and visceral fat. Twenty studies comprising 15,763 subjects were included, consisting of the relationship with NAFLD (n = 15) and the relationship with hepatic steatosis (n = 7). All studies reported a positive relationship between NAFLD and visceral fat. For hepatic steatosis regardless of severity, only one study reported no correlation with visceral fat. Further results showed that visceral fat is more related to NAFLD and hepatic steatosis in females than males. More studies including NAFLD of different stages must be performed in the future to validate the degree of association between visceral fat and NAFLD at all stages as well as this relationship difference between genders.

The effect of obstructive sleep apnea on fatty liver disease may be obscured by alcohol consumption: An ordinal logistic regression analysis

BACKGROUND

Obstructive sleep apnea (OSA) is closely associated with non-alcoholic fatty liver disease (NAFLD). The current definition of NAFLD cannot exclude the involvement of alcohol consumption in the development of fatty liver disease (FLD), but alcohol can aggravate OSA and participate in steatosis. There is limited evidence on the relationship between OSA and alcohol and its effect on FLD severity.

OBJECTIVE

To determine the effect of OSA on FLD severity based on ordinal responses, and its relationship with alcohol consumption, in order to develop strategies for the prevention and treatment of FLD.

METHODS

Patients with chief complaints of "snoring" who underwent polysomnography and abdominal ultrasound between January 2015 and October 2022 were selected. A total of 325 cases were divided into three groups according to abdominal ultrasound results: no FLD (n = 66), mild FLD (n = 116), and moderately severe FLD (n = 143) group. Patients were also categorized into alcoholic and nonalcoholic groups. Univariate analysis was used to examine the correlation between OSA and FLD severity. Multivariate ordinal logistic regression analysis was further used to identify the determinants of FLD severity and differences between the alcoholic and nonalcoholic groups.

RESULTS

A higher proportion of moderately severe FLD was observed in the group with an apnea/hypopnea index (AHI) > 30 compared to the AHI<15 group in all participants and in the nonalcoholic population (all p < 0.05). There was no significant difference among these groups in the alcoholic population. Ordinal logistic regression analysis found that in all participants, age [OR = 0.966(0.947-0.986)], BMI [OR = 1.293 (1.205-1.394)], diabetes mellitus [OR = 1.932(1.132-3.343)], hyperlipidemia [OR = 2.432(1.355-4.464)], severe OSA [OR = 2.36(1.315-4.259)] (all p < 0.05) were the independent risk factors for more severe FLD. However, different risk factors applied according to alcohol consumption. In addition to age and BMI, the independent risk factors for the alcoholic group also included diabetes mellitus [OR = 3.323(1.494-7.834)] while in the non-alcoholic group risk factors included hyperlipidemia [OR = 4.094(1.639-11.137)], and severe OSA[OR = 2.956(1.334-6.664)] (all p < 0.05).

CONCLUSION

Severe OSA is an independent determinant for developing more severe NAFLD in nonalcoholic population, and alcohol consumption may obscure the effect of OSA on the progression of FLD.

Serum and supplemental vitamin D levels and insulin resistance in T2DM populations: a meta-analysis and systematic review

Observational studies have shown a negative correlation between Vitamin D level and the likelihood of developing insulin resistance (IR) and/or diabetes over time, yet evidence remains inconsistent. In this meta-analysis and systematic review, we strive to define the potential association between serum or supplemental Vitamin D Levels and insulin resistance respectively, as well as the contribution of Vitamin D to type 2 diabetes, and to summarize the biologic plausibility of Vitamin D. Four databases (PubMed, Embase, Cochrane Library, and Web of Science) were searched for this Systematic Literature Review (SLR) to find appropriate observational studies and clinical trials published in English through to July 2022. EndNote (version X9) is used to manage the literature search results. We calculated Standard Mean Differences (SMDs) and Risk Ratios (RRs) with their 95% Confidence Intervals (CIs), separately, for continuous and dichotomous outcomes. The correlation coefficients were normalized to z values through Fisher's z-transformation to calculate the relevant statistics. Meta-analyses were carried out for all comparisons, based on a random-effects pooling model. Data analysis was performed using RevMan (version 5.3) and STATA (version 15.1). All statistical tests were two-sided, with P < 0.05 were regarded as significant. In our current meta-analysis, there are 18 RCTs and 20 observational studies including 1243 and 11,063 participants respectively. In the overall analysis, the diabetic with Vitamin D supplement treatment group showed significantly improve serum insulin (SMD =  - 0.265, 95% CI - 0.394 to - 0.136, P < 0.05), glucose (SMD =  - 0.17, 95% CI - 0.301to - 0.039, P < 0.05) and HOMA-IR (SMD =  - 0.441, 95% CI - 0.582 to - 0.3, P < 0.05) compared with the routine treatment group. Correlation analysis results showed that all three outcomes were significantly correlated in a negative manner with raised Vitamin D (insulin: r =  - 0.08 95% =  - 0.12 to - 0.04; glucose: r =  - 0.06 95% =  - 0.11 to - 0.01; HOMA-IR: r =  - 0.08 95% =  - 0.09 to - 0.06). Results of overall analysis proved that vitamin D has shown significant effect on regulates insulin resistance, and there is a significant inverse association between serum Vitamin D level and IR. Vitamin D supplementation is expected to be integrated into conventional medical approaches to prevent type 2 diabetes and to mitigate the burden of diabetes for individuals and society.PROSPERO registration number: CRD42022348295.

Triglyceride and glucose index is a simple and easy-to-calculate marker associated with nonalcoholic fatty liver disease

OBJECTIVE

The aim of this study was to evaluate the relationship between the triglyceride and glucose (TyG) index and nonalcoholic fatty liver disease (NAFLD) using a large, population-based cohort study database.

METHODS

A total of 52,575 participants were enrolled from 2007 to 2013 in the Kangbuk Samsung Health Study cohort. The presence of NAFLD was ascertained by ultrasonography in the absence of other known liver diseases.

RESULTS

Over a median 5.1 years of follow-up, 7,292 participants (13.87%) were diagnosed with NAFLD. In a multivariate-adjusted model, the hazard ratio for NAFLD of the TyG index was 1.413 (95% CI: 1.349-1.480) in the first 6 months, 1.480 (95% CI: 1.408-1.556) in months 6 to 12, 1.427 (95% CI: 1.370-1.485) in months 12 to 18, and 1.246 (95% CI: 1.159-1.339) in months >18. The hazard ratios of triglycerides, glucose, fatty liver index, and homeostatic model assessment of insulin resistance for NAFLD in months >18 were 1.124 (95% CI: 1.061-1.190), 1.037 (95% CI: 0.970-1.109), 1.508 (95% CI: 1.417-1.605), and 1.177 (95% CI: 1.116-1.242), respectively. The NAFLD-free rate decreased with increasing TyG index quartile (p < 0.001). The TyG index level from which the risk of NAFLD increased appeared to be 8.24.

CONCLUSIONS

This study found that the TyG index is a simple and easy-to-calculate marker associated with NAFLD.

Vitamin D levels are not associated with non-alcoholic fatty liver disease severity in a Brazilian population

Some epidemiological evidence suggests an inverse correlation between non-alcoholic fatty liver disease (NAFLD) frequency and vitamin D levels. Likewise, a beneficial effect of vitamin D on diabetes mellitus (DM) and insulin resistance has been observed, but this is an unsolved issue. Thus, we aimed to investigate the prevalence of hypovitaminosis D in a NAFLD Brazilian population and its association with disease severity and presence of comorbidities. In a cross-sectional study, the clinical, biochemical and histological parameters of 139 NAFLD patients were evaluated according to two different cut-off points of serum 25-hydroxyvitamin D levels (20 ng/mL and 30 ng/mL). The mean age of the population was 56 ± 16 years, most patients were female (83%), 72% had hypertension, 88% dyslipidemia, 46% DM, 98% central obesity, and 82% metabolic syndrome. Serum vitamin D levels were < 30 ng/mL in 78% of the patients, and < 20 ng/mL in 35%. The mean vitamin D level was 24.3 ± 6.8 ng/mL. The comparison between the clinical, biochemical and histological characteristics of the patients according to the levels of vitamin D showed no significant difference. Most patients with NAFLD had hypovitaminosis D, but low vitamin D levels were not related to disease severity and the presence of comorbidities.