Differential effects of different vitamin D replacement strategies in patients with diabetes.

BACKGROUND: The optimal treatment regimen for correcting vitamin D insufficiency in diabetic patients has not been established.

METHODS: Two hundred and forty four adult diabetic patients with vitamin D insufficiency were enrolled to receive: Ergocalciferol (D2) 50,000 IU daily over 10 days (500,000 IU) followed by Calcichew D3 (calcium carbonate/Cholecalciferol) BID (~24,000 IU cholecalciferol/month) (ECC) (n=53); Cholecalciferol (D3) 40,000 IU daily over 10 days (400,000 IU) followed by Calcichew D3 BID (~24,000 IU cholecalciferol/month) (CCC) (n=94) or Cholecalciferol 40,000 IU daily over 10 days (400,000 IU) followed by Cholecalciferol 40,000 IU monthly (CC) (n=97). The 25(OH)D, HbA1c, lipids, blood pressure and eGFR were assessed at baseline and after a mean follow up of 8.0±4.0 months.

RESULTS: Treatment increased 25(OH)D concentrations significantly in ECC (17.4±13.8 vs 29.9±9.6 ng/ml, P<0.0001), CCC (14.2±6.6 vs 30.9±13.1 ng/ml, p<0.0001) and CC (13.5±8.4 vs 33.9±14.4 ng/ml, P<0.0001). The relative increase in 25(OH)D was significantly lower with ECC compared to CC (+14.6±12.2 vs +20.6±15.0, P=0.01) and the majority of subjects in the ECC group (63%) remained vitamin D deficient (25(OH)D <30 ng/ml) compared to CCC (46%) and CC (36%) (P=0.0005).

CONCLUSION: This study demonstrates that relatively aggressive treatment regimens of both vitamin D2 and D3 increase 25(OH)D concentrations in diabetic patients, but the ability to raise 25(OH)D status to 'sufficient' levels is inadequate in a large proportion of individuals.