Diabetic cardiomyopathy: Pathophysiology, theories and evidence to date

The prevalence of type 2 diabetes(T2D)has increased worldwide and doubled over the last two decades.It features among the top 10 causes of mortality and morbidity in the world.Cardiovascular disease is the leading cause of complications in diabetes and within this,heart failure has been shown to be the leading cause of emergency admissions in the United Kingdom.There are many hypotheses and well-evidenced mechanisms by which diabetic cardiomyopathy as an entity develops.This review aims to give an overview of these mechanisms,with particular emphasis on metabolic inflexibility.T2D is associated with inefficient substrate utilisation,an inability to increase glucose metabolism and dependence on fatty acid oxidation within the diabetic heart resulting in mitochondrial uncoupling,glucotoxicity,lipotoxicity and initially subclinical cardiac dysfunction and finally in overt heart failure.The review also gives a concise update on developments within clinical imaging,specifically cardiac magnetic resonance studies to characterise and phenotype early cardiac dysfunction in T2D.A better understanding of the pathophysiology involved provides a platform for targeted therapy in diabetes to prevent the development of early heart failure with preserved ejection fraction.

Age at diagnosis of type 2 diabetes and cardiovascular risk factor profile:A pooled analysis

BACKGROUND The diagnosis of type 2 diabetes(T2D)in younger adults,an increasingly common public health issue,is associated with a higher risk of cardiovascular complications and mortality,which may be due to a more adverse cardiovascular risk profile in individuals diagnosed at a younger age.AIM To investigate the association between age at diagnosis and the cardiovascular risk profile in adults with T2D.METHODS A pooled dataset was used,comprised of data from five previous studies of adults with T2D,including 1409 participants of whom 196 were diagnosed with T2D under the age of 40 years.Anthropometric and blood biomarker measurements included body weight,body mass index(BMI),waist circumference,body fat percentage,glycaemic control(HbA1c),lipid profile and blood pressure.Univariable and multivariable linear regression models,adjusted for diabetes duration,sex,ethnicity and smoking status,were used to investigate the association between age at diagnosis and each cardiovascular risk factor.RESULTS A higher proportion of participants diagnosed with T2D under the age of 40 were female,current smokers and treated with glucose-lowering medications,compared to participants diagnosed later in life.Participants diagnosed with T2D under the age of 40 also had higher body weight,BMI,waist circumference and body fat percentage,in addition to a more adverse lipid profile,compared to participants diagnosed at an older age.Modelling results showed that each one year reduction in age at diagnosis was significantly associated with 0.67 kg higher body weight[95%confidence interval(CI):0.52-0.82 kg],0.18 kg/m^(2) higher BMI(95%CI:0.10-0.25)and 0.32 cm higher waist circumference(95%CI:0.14-0.49),after adjustment for duration of diabetes and other confounders.Younger age at diagnosis was also significantly associated with higher HbA1c,total cholesterol,low-density lipoprotein cholesterol and triglycerides.CONCLUSION The diagnosis of T2D earlier in life is associated with a worse cardiovascular risk factor profile,compared to those diagnosed later in life.