The 2012 CDA-CIHR INMD young investigator award lecture: dysfunction of adipose tissues and the mechanisms of ectopic fat deposition in type 2 diabetes

Metabolomic signatures for visceral adiposity and dysglycaemia in Asian Chinese and Caucasian European adults: the cross-sectional TOFI_Asia study

BACKGROUND

Asian Chinese are more susceptible to deposition of visceral adipose tissue (VAT) and type 2 diabetes (T2D) development than European Caucasians when matched for gender, age and body mass index (BMI). Our aims were: (i) characterise the ethnicity-specific metabolomic signature of visceral adiposity measured by dual energy X-ray absorptiometry (DXA) and fasting plasma glucose (FPG), and (ii) identify individuals susceptible to worse metabolic health outcomes.

METHODS

Fasting plasma samples from normoglycaemic (n = 274) and prediabetic (n = 83) participants were analysed with liquid chromatography-mass spectrometry using untargeted metabolomics. Multiple linear regression adjusting for age, gender and BMI was performed to identify metabolites associated with FPG and VAT calculated as percentage of total body fat (%VAT_TBF) in each ethnic group. Metabolic risk groups in each ethnicity were stratified based on the joint metabolomic signature for FPG and %VAT_TBF and clinically characterised using partial least squares-discriminant analysis (PLS-DA) and t-tests.

RESULTS

FPG was correlated with 40 and 110 metabolites in Caucasians and Chinese respectively, with diglyceride DG(38:5) (adjusted β = 0.29, p = 3.00E-05) in Caucasians and triglyceride TG(54:4) (adjusted β = 0.28, p = 2.02E-07) in Chinese being the most significantly correlated metabolite based on the p-value. %VAT_TBF was correlated with 85 and 119 metabolites in Caucasians and Chinese respectively, with TG(56:2) (adjusted β = 0.3, p = 8.25E-09) in Caucasians and TG(58:3) (adjusted β = 0.25, p = 2.34E-08) in Chinese being the most significantly correlated. 24 metabolites associated with FPG were common to both ethnicities including glycerolipid species. 67 metabolites associated with %VAT_TBF were common to both ethnicities including positive correlations with dihydroceramide, sphingomyelin, glycerolipid, phosphatidylcholine, phosphatidylethnolamine, and inverse correlations with ether-linked phosphatidylcholine. Participant re-stratification found greater total and central adiposity, worse clinical lipid profiles, higher serum glucoregulatory peptides and liver enzymes in normal fasting glucose (NFG) individuals with a prediabetic metabolomic profile than NFG individuals with a normoglycaemic metabolomic profile in both ethnicities.

CONCLUSIONS

Untargeted metabolomics identified common and disparate metabolites associated with FPG and %VAT_TBF, with an ethnic-dimorphic signature for these metabolic traits. These signatures could improve risk stratification and identify NFG individuals with an adverse cardiometabolic and T2D risk profile.

Targeting the gut to treat obesity and its metabolic comorbidities: focus on bariatric surgery - view from the chair

Over the past decade, bariatric surgery emerged as the most effective treatment modality for obesity and its complications, especially type 2 diabetes. Initially introduced on the basis of their capacity to restrict food intake and/or induce dietary fat malabsorption, the current bariatric surgery procedures result in many more physiological changes that may also partly explain their potent and sustained anti-obesity and anti-diabetic effects. In the session 2 of the 17th International Symposium of the Université Laval Research Chair in Obesity, outstanding speakers have provided insight into novel clinical and pathophysiological aspects in bariatric surgery. Dr Blandine Laferrère discussed the growing body of evidence implicating incretin hormones in the anti-diabetic effects of bariatric surgery and Dr Hans-Rudolf Berthoud explored emerging evidence suggesting that bariatric surgery may reset the defended body mass set point. As data are rapidly accruing about the beneficial effects of bariatric surgery, these procedures not only take a greater place in clinical practice, but they also offer outstanding occasions to peek into the intricate and complex links between diet and gastrointestinal track, and obesity and its complications.