We found that OC was negatively associated with diabetes only in women with low PTH (OR = 0.957, 95% CI = 0.933–0.982), whereas the positive association between OC and hypercholesterolemia remained significant in both women with low PTH (OR = 1.024, 95% CI = 1.002–1.047) and women with high PTH (OR = 1.049, 95% CI = 1.015–1.084 for hypercholesterolemia). Here, PTH is linked to familial hypercholesterolemia.