PTH and Insulin resistance: There is evidence that lower levels of 25(OH)D and higher levels of PTH are associated with cardiovascular risk factors, including hyperglycaemia, insulin resistance, type 2 diabetes, dyslipidaemia and high blood pressure,[5]–[12] but to our knowledge no previous study has examined associations of all three of 25(OH)D, PTH and calcium with cardiovascular risk factors to.