Aims/hypothesis
A recent genome-wide association study identified the SLC30A8 rs13266634 polymorphism encoding an Arg325Trp polymorphism in the zinc transporter protein member 8 (ZnT-8) to be associated
with type 2 diabetes. Here, we investigate whether the polymorphism is related to altered insulin release in response to intravenous
and oral glucose loads in non-diabetic offspring of type 2 diabetic patients.
Methods
We genotyped SLC30A8 rs13266634 in 846 non-diabetic offspring of type 2 diabetic patients from five different white populations: Danish (n = 271), Finnish (n
= 217), German (n = 149), Italian (n
= 109) and Swedish (n
= 100). Participants were subjected to both IVGTTs and OGTTs, and measurements of insulin sensitivity.
Results
Homozygous carriers of the major type 2 diabetes C risk-allele showed a 19% decrease in first-phase insulin release (0–10 min)
measured during the IVGTT (CC 3,624 ± 3,197; CT 3,763 ± 2,674; TT 4,478 ± 3,032 pmol l−1 min−1, mean ± SD; p = 0.007). We found no significant genotype effect on insulin release measured during the OGTT or on estimates of insulin
sensitivity.
Conclusions/interpretation
Of European non-diabetic offspring of type 2 diabetes patients, 46% are homozygous carriers of the Arg325Trp polymorphism
in ZnT-8, which is known to associate with type 2 diabetes. These diabetes-prone offspring are characterised by a 19% decrease
in first-phase insulin release following an intravenous glucose load, suggesting a role for this variant in the pathogenesis
of pancreatic beta cell dysfunction.
Keywords Beta cell dysfunction - Genetics - Insulin - Offspring - Polymorphism -
SLC30A8
- Type 2 diabetes - Zinc transporter protein member 8 - ZnT-8