ApoC-III and ectopic fat accumulation in individuals with type 2 diabetes: an exploratory analysis from the MEDEA randomised controlled study

Aims/hypothesis: We aimed to investigate the effects of an isoenergetic multifactorial diet, previously shown to reduce liver and pancreatic fat content, compared with a monounsaturated fatty acid (MUFA)-rich diet, on plasma apolipoprotein C-III (ApoC-III) levels and their relationship with ectopic fat and beta cell function in people with type 2 diabetes. Methods: In this randomised controlled, parallel group study, 36 individuals with type 2 diabetes (20 men, 16 women), aged 35-75 years, were assigned to an 8 week intervention with either an isoenergetic MUFA-rich diet (n=16) or a multifactorial diet rich in MUFA, polyunsaturated fats, fibre, polyphenols and vitamins (n=20). Fasting and postprandial (3 h test meal reflecting the assigned diet) plasma glucose, insulin and ApoC-III concentrations were measured before and after the intervention. Beta cell function was assessed as the insulin-to-glucose total AUC ratio. Liver and pancreatic fat content were quantified using magnetic resonance techniques. Results: Compared with the MUFA diet, the multifactorial diet led to a decrease (8 week minus baseline) in fasting ApoC-III levels (-0.006 ± 0.040 vs +0.007 ± 0.048 g/l, p=0.070) and postprandial ApoC-III AUC (-1.34 ± 6.01 vs +1.60 ± 5.56 g/l × 180 min, p=0.043). Regardless of dietary intervention, changes in fasting ApoC-III positively correlated with changes in liver fat (r=0.357, p=0.032) and pancreatic fat (r=0.385, p=0.020). Both fasting and postprandial ApoC-III changes were inversely correlated with beta cell function (r=-0.384, p=0.026; r=-0.402, p=0.018, respectively). Conclusions/interpretation: A multifactorial diet significantly reduced plasma ApoC-III levels in individuals with type 2 diabetes. Independent of dietary intervention, lower ApoC-III levels were associated with reduced liver and pancreatic fat accumulation and improved beta cell function. Trial registration: ClinicalTrials.gov NCT03380416.