Scavenger receptor class B type I (SCARB1) was described as the first HDL receptor. Increasing evidence indicates that SCARB1 plays additional roles particularly in type 2 diabetes mellitus. Our aim was to determine whether the presence of an exon 1 (G A) polymorphism at the SCARB1 gene modifies the insulin sensitivity to dietary fat.

Methods: We studied 59 healthy volunteers (30 men and 29 women, 42 G/G homozygous and 17 G/A heterozygous). Subjects consumed 3 diets during 4-weeks each: a saturated fatty acid (SFA)-rich diet (38% fat, 20% SFA), followed by a carbohydrate (CHO)-rich diet (30% fat, 55% carbohydrate) or a monounsaturated fatty acid (MUFA)-rich diet (38% fat, 22% MUFA) following a randomized crossover design. For each diet, we investigated peripheral insulin sensitivity with the insulin suppression test.

Results: Steady-state plasma glucose (SSPG) following the MUFA diet was lower in G/A compared with G/G subjects (P = 0.030). This effect was not observed after CHO and SFA diets (P = 0.177 and P = 0.957, respectively). Plasma non-esterified free fatty acid values were lower in subjects carrying the A allele for all the diet periods.

Conclusions: Our findings show that carriers of the G/A genotype have significant increases in insulin sensitivity following a MUFA-rich diet compared with G/G individuals.