Sex differences in intraorgan fat levels and hepatic lipid metabolism: implications for cardiovascular health and remission of type 2 diabetes after dietary weight loss

The moderating effect of cardiometabolic factors on the association between hepatic and intrapancreatic fat

OBJECTIVE

Previous studies have investigated the association between hepatic fat and intrapancreatic fat deposition (IPFD); however, results have been inconclusive. The presence of cardiometabolic factors in certain subpopulations could explain this discrepancy. The aim of the present study was to use moderation analyses to determine the conditions under which hepatic fat is associated with IPFD.

METHODS

All participants underwent 3T abdominal magnetic resonance imaging (MRI) and spectroscopy. Hepatic fat and IPFD were manually quantified by independent raters. Moderation analyses were performed with adjustment for sex and ethnicity.

RESULTS

There were 367 participants included. Adjusted analyses of the overall cohort revealed that age, glycated hemoglobin (HbA1c), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides were significant moderators (p < 0.05) of the association between hepatic fat and IPFD. Ranges of significance included age < 61 years, HbA1c < 45 mmol/mol, LDL-C < 157 mg/dL, HDL-C > 36 mg/dL, and triglycerides < 203 mg/dL.

CONCLUSIONS

The association between hepatic fat and IPFD is generally present in young and middle-aged adults with good cardiometabolic health, whereas the link between the two fat depots becomes uncoupled in older adults or individuals with cardiometabolic risk factors.

5-year follow-up of the randomised Diabetes Remission Clinical Trial (DiRECT) of continued support for weight loss maintenance in the UK: an extension study

BACKGROUND

In DiRECT, a randomised controlled effectiveness trial, weight management intervention after 2 years resulted in mean weight loss of 7·6 kg, with 36% of participants in remission of type 2 diabetes. Of 36 in the intervention group who maintained over 10 kg weight loss at 2 years, 29 (81%) were in remission. Continued low-intensity dietary support was then offered up to 5 years from baseline to intervention participants, aiming to maintain weight loss and gain clinical benefits. This extension study was designed to provide observed outcomes at 5 years.

METHODS

The DiRECT trial took place in primary care practices in the UK. Participants were individuals aged 20-65 years who had less than 6 years' duration of type 2 diabetes, a BMI greater than 27 kg/m2, and were not on insulin. The intervention consisted of withdrawal of antidiabetic and antihypertensive drugs, total diet replacement (825-853 kcal per day formula diet for 12-20 weeks), stepped food reintroduction (2-8 weeks), and then structured support for weight-loss maintenance. After sharing the 2-year results with all participants, UK National Health Service data were collected annually until year 5 from remaining intervention participants who received low-intensity dietary support, intervention withdrawals, and the original randomly allocated groups. The primary outcome was remission of type 2 diabetes; having established in the DiRECT trial that sustained weight loss was the dominant driver of remission, this was assumed for the Extension study. The trial is registered with the ISRCTN registry, number 03267836.

FINDINGS

Between July 25, 2014, and Aug 5, 2016, 149 participants were randomly assigned to the intervention group and 149 were assigned to the control group in the original DiRECT study. After 2 years, all intervention participants still in the trial (101 [68%] of 149) were approached to receive low-intensity support for a further 3 years. 95 (94%) of 101 were able to continue and consented and were allocated to the DiRECT extension group. 54 participants were allocated to the non-extension group, where intervention was withdrawn. At 5 years, DiRECT extension participants (n=85) lost an average of 6·1 kg, with 11 (13%) of 85 in remission. Compared with the non-extension group, DiRECT extension participants had more visits with HbA1c <48 mmol/mol (<6·5%; 36% vs 17%, p=0·0004), without glucose-lowering medication (62% vs 30%, p<0·0001), and in remission (34% vs 12%, p<0·0001). Original control participants (n=149) had mean weight loss 4·6 kg (n=82), and 5 (5%) of 93 were in remission. Compared with control participants, original intervention participants had more visits with weight more than 5% below baseline (61% vs 29%, p<0·0001), HbA1c below 48 mmol/mol (29% vs 15%, p=0·0002), without antidiabetic medication (51% vs 16%, p<0·0001), and in remission (27% vs 4%, p<0·0001). Of those in remission at year 2, 26% remained in remission at 5 years. Serious adverse events in the original intervention group (4·8 events per 100 patient-years) were under half those in the control group (10·2 per 100 patient-years, p=0·0080).

INTERPRETATION

The extended DiRECT intervention was associated with greater aggregated and absolute weight loss, and suggested improved health status over 5 years.

FUNDING

Diabetes UK.

Very low calorie diets and total diet replacement in type 2 diabetes: where are we now?

Management of type 2 diabetes has now been simplified by the understanding that the condition is caused by excess fat in the liver together with suppression of beta cell function by the associated excess liver export of fat. These factors can be reversed by substantial weight loss leading to remission in the early years after diagnosis, or at least major decrease in cardiovascular risks and improvement in glucose control for all. Weight loss by any means is successful, but it is most easily achieved by rapid action using a low or very low calorie diet of around 800 kcal/day followed by sustained modest restraint of dietary habits. Oral hypoglycaemic agents and one antihypertensive drug can be withdrawn on day 1 of the weight loss diet, raising the importance of appropriate deprescribing.

Cardiovascular risk in diabetes mellitus: epidemiology, assessment and prevention

Cardiovascular diseases (CVDs) are the leading causes of morbidity and mortality in individuals with type 2 diabetes mellitus (T2DM). Secular changes in CVD outcomes have occurred over the past few decades, mainly due to a decline in the incidence of ischaemic heart disease. The onset of T2DM at a young age (<40 years), leading to a greater number of life-years lost, has also become increasingly common. Researchers are now looking beyond established risk factors in patients with T2DM towards the role of ectopic fat and, potentially, haemodynamic abnormalities in mediating important outcomes (such as heart failure). T2DM confers a wide spectrum of risk and is not necessarily a CVD risk equivalent, indicating the importance of risk assessment strategies (such as global risk scoring, consideration of risk-enhancing factors and assessment of subclinical atherosclerosis) to inform treatment. Data from epidemiological studies and clinical trials demonstrate that successful control of multiple risk factors can reduce the risk of CVD events by ≥50%; however, only ≤20% of patients achieve targets for risk factor reduction (plasma lipid levels, blood pressure, glycaemic control, body weight and non-smoking status). Improvements in composite risk factor control with lifestyle management (including a greater emphasis on weight loss interventions) and evidence-based generic and novel pharmacological therapies are therefore needed when the risk of CVD is high.

Hepatic Fat and Macrophages Are Increased in Livers of Diabetic Patients without Non-Alcoholic Fatty Liver Disease

INTRODUCTION

Diabetes mellitus (DM), especially type 2, is strongly associated with non-alcoholic fatty liver disease (NAFLD). Recent studies indicate that particularly in DM patients, "simple" liver steatosis can progress into more severe disease. However, little is known about putative hepatic histopathological changes in DM patients without NAFLD. In this study, we therefore analysed fat content and inflammatory cell infiltration in the livers of deceased DM and non-DM patients without NAFLD, and analysed age/sex effects hereon.

METHODS

Hepatic fat and inflammatory cells were studied through (immuno)histochemical analysis in liver tissue from 24 DM patients and 66 non-diabetic controls, without histopathological characteristics of NAFLD.

RESULTS

We observed a 2-fold increase in fat percentage/mm2 and a near 5-fold increase in the number of fat-containing cells/mm2 in DM patients compared to non-diabetic controls. Fat content was significantly higher in patients with type 2 DM, but not type 1 DM, compared to non-diabetic controls, while the number of CD68+ cells/mm2 was significantly elevated in both DM groups.

CONCLUSION

Hepatic fat and number of macrophages are increased in patients with DM without NAFLD, which may reflect a higher risk on development of steatosis and steatohepatitis.

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.

Sex differences in endocannabinoids during 3 years of Mediterranean diet intervention: Association with insulin resistance and weight loss in a population with metabolic syndrome

Background

Excess circulating endocannabinoids (eCBs) and imbalanced N-acylethanolamines (NAEs) related eCBs abundance could influence dietary weight loss success. We aimed to examine sex differences in the impact of a 3-years Mediterranean diet (MedDiet) intervention on circulating eCBs, NAEs and their precursor fatty acids, and to analyze the interplay between changes in eCBs or NAEs ratios, insulin resistance and the achievement of clinically meaningful weight reductions.

Methods

Prospective cohort study in a subsample of N = 105 participants (54.3% women; 65.6 ± 4.6 years) with overweight or obesity and metabolic syndrome that underwent a 3-years MedDiet intervention (PREDIMED-Plus study). Plasma eCBs and NAEs, including 2-arachidonoylglycerol (2-AG), anandamide (AEA), oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), fatty acids, diet, glycemic homeostasis (including the assessment of insulin resistance-HOMA-IR), and cardiovascular risk markers were monitored (at 0-6-12-36 months).

Results

Mediterranean diet adherence increased in both sexes and remained high during the 3 years of follow-up. Reductions in body weight, glycemic and cardiovascular parameters were larger in men than in women. Women presented higher concentrations of NAEs than men throughout the study. In both sexes, AEA and other NAEs (including OEA, and PEA) decreased after 6 months (for AEA: −4.9%), whereas the ratio OEA/AEA increased after 1 year (+5.8%). Changes in 2-AG (−3.9%) and the ratio OEA/PEA (+8.2%) persisted over the 3 years of follow-up. In women, 6-months changes in AEA (OR = 0.65) and the ratio OEA/AEA (OR = 3.28) were associated with the achievement of 8% weight reductions and correlated with HOMA-IR changes (r = 0.29 and r = −0.34). In men, OEA/PEA changes were associated with 8% weight reductions (OR = 2.62) and correlated with HOMA-IR changes (r = −0.32).

Conclusion

A 3-years MedDiet intervention modulated plasma concentrations of eCBs and NAEs. Changes in AEA and in the relative abundance of NAEs were associated with clinically meaningful weight reductions. However, marked sex differences were identified in eCBs and NAEs, as well as in the efficacy of the intervention in terms of glycemic and cardiovascular parameters, which could be related to post-menopause alterations in glucose metabolism. These findings support a sex-balanced research strategy for a better understanding of the mechanisms underlying the regulation of body weight loss.

Age- and sex-specific effects of a long-term lifestyle intervention on body weight and cardiometabolic health markers in adults with prediabetes: results from the diabetes prevention study PREVIEW

AIMS/HYPOTHESIS

Lifestyle interventions are the first-line treatment option for body weight and cardiometabolic health management. However, whether age groups or women and men respond differently to lifestyle interventions is under debate. We aimed to examine age- and sex-specific effects of a low-energy diet (LED) followed by a long-term lifestyle intervention on body weight, body composition and cardiometabolic health markers in adults with prediabetes (i.e. impaired fasting glucose and/or impaired glucose tolerance).

METHODS

This observational study used longitudinal data from 2223 overweight participants with prediabetes in the multicentre diabetes prevention study PREVIEW. The participants underwent a LED-induced rapid weight loss (WL) period followed by a 3 year lifestyle-based weight maintenance (WM) intervention. Changes in outcomes of interest in prespecified age (younger: 25-45 years; middle-aged: 46-54 years; older: 55-70 years) or sex (women and men) groups were compared.

RESULTS

In total, 783 younger, 319 middle-aged and 1121 older adults and 1503 women and 720 men were included in the analysis. In the available case and complete case analyses, multivariable-adjusted linear mixed models showed that younger and older adults had similar weight loss after the LED, whereas older adults had greater sustained weight loss after the WM intervention (adjusted difference for older vs younger adults -1.25% [95% CI -1.92, -0.58], p<0.001). After the WM intervention, older adults lost more fat-free mass and bone mass and had smaller improvements in 2 h plasma glucose (adjusted difference for older vs younger adults 0.65 mmol/l [95% CI 0.50, 0.80], p<0.001) and systolic blood pressure (adjusted difference for older vs younger adults 2.57 mmHg [95% CI 1.37, 3.77], p<0.001) than younger adults. Older adults had smaller decreases in fasting and 2 h glucose, HbA1c and systolic blood pressure after the WM intervention than middle-aged adults. In the complete case analysis, the above-mentioned differences between middle-aged and older adults disappeared, but the direction of the effect size did not change. After the WL period, compared with men, women had less weight loss (adjusted difference for women vs men 1.78% [95% CI 1.12, 2.43], p<0.001) with greater fat-free mass and bone mass loss and smaller improvements in HbA1c, LDL-cholesterol and diastolic blood pressure. After the WM intervention, women had greater fat-free mass and bone mass loss and smaller improvements in HbA1c and LDL-cholesterol, while they had greater improvements in fasting glucose, triacylglycerol (adjusted difference for women vs men -0.08 mmol/l [-0.11, -0.04], p<0.001) and HDL-cholesterol.

CONCLUSIONS/INTERPRETATION

Older adults benefited less from a lifestyle intervention in relation to body composition and cardiometabolic health markers than younger adults, despite greater sustained weight loss. Women benefited less from a LED followed by a lifestyle intervention in relation to body weight and body composition than men. Future interventions targeting older adults or women should take prevention of fat-free mass and bone mass loss into consideration.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01777893.

The Role of Beta Cell Recovery in Type 2 Diabetes Remission

Type 2 diabetes (T2D) has been considered a relentlessly worsening disease, due to the progressive deterioration of the pancreatic beta cell functional mass. Recent evidence indicates, however, that remission of T2D may occur in variable proportions of patients after specific treatments that are associated with recovery of beta cell function. Here we review the available information on the recovery of beta cells in (a) non-diabetic individuals previously exposed to metabolic stress; (b) T2D patients following low-calorie diets, pharmacological therapies or bariatric surgery; (c) human islets isolated from non-diabetic organ donors that recover from "lipo-glucotoxic" conditions; and (d) human islets isolated from T2D organ donors and exposed to specific treatments. The improvement of insulin secretion reported by these studies and the associated molecular traits unveil the possibility to promote T2D remission by directly targeting pancreatic beta cells.

Dysglycemia in young women attenuates the protective effect against fatty liver disease

INTRODUCTION

Sexual dimorphism has been reported in non-alcoholic fatty liver disease (NAFLD), similar to the sex differences evident with cardiovascular disease. Type 2 diabetes mellitus (T2D) significantly increases the risk and severity of NAFLD, but there is scarce information on whether T2D or altered glucose metabolism can modify the prevalence of NAFLD in men and women of reproductive age.

PURPOSE

To investigate the relationship between age, sex and NAFLD in subjects with and without dysglycemia.

MATERIALS AND METHODS

We analyzed 2,790 patients. NAFLD was characterized using established diagnostic criteria: one or more positive results on the fatty liver index and hepatic ultrasound. Liver fibrosis (liver stiffness measurement [LSM] ≥8.0 kPa) was assessed by Fibroscan^®. For analysis purposes, we included both T2D and prediabetes under the predefined condition of dysglycemia.

RESULTS

The global prevalence of NAFLD was higher in men than in women (50% and 34%; P<0.001), and the prevalence increased with age in both sexes. Older women (≥ 50 years) had a higher prevalence than younger women (<50 years), both in the overall cohort and in non-dysglycemic subjects. In dysglycemic subjects, the prevalence of NAFLD was slightly higher in men (68% vs 61%, p=0.021); in younger subjects, there were no differences in the prevalence of NAFLD between men and women (68% vs 64%, respectively; p=0.635). We found an interaction between dysglycemia and female sex (odds ratio [OR] 1.6 95% confidence interval [CI] 1.0-2.4, p=0.030), and between and age ≥50 years (OR 0.6, 95% CI 0.3-1.0, p=0.046). The global prevalence of LSM ≥8.0 kPa was higher in men compared with women (8% vs 4%; p< 0.001). This prevalence increased with age, mainly in men. We did not find any association between liver fibrosis and age and gender.

CONCLUSIONS

While the global prevalence of NAFLD is higher in men than in women across all ages, younger women with dysglycemia have a similar risk of developing NAFLD as men of a similar age. Therefore, the presence of dysglycemia may erase the protective effect of female sex against fatty liver disease.