Attenuated PTH Responsiveness to Vitamin D Deficiency among Patients with Type 2 Diabetes and Chronic Hyperglycemia

Abstract

Background The short and long-term relationship between hyperglycemia and PTH level among patients suffering from both diabetes type 2 and vitamin D deficiency were evaluated. Methods This was a cross sectional study performed at Dubai Diabetes Center, UAE. To demonstrate the relationship between hyperglycemia and PTH level, subjects with type 2 diabetes and vitamin D deficiency (124 adults) were divided into 4 groups based on their FPG and HbA1c levels. Results Mean vitamin D and PTH levels among subjects with HbA1c ≤ 7% (53 mmol/mol) were 14.05 ng/ml and 19.51 pg/ml respectively. On the other hand, mean vitamin D and PTH levels among subjects with HbA1c ≥ 10% (86 mmol/mol) were significantly lower at 11.77 ng/ml and 17.75 pg/ml respectively. The product of vitamin D and PTH among subjects with an HbA1c ≤ 7% (53 mmol/mol) was 250.380, compared with only 197.710 among subjects with HbA1c ≥ 10 (86 mmol/mol). Regression analysis for subjects older than 50 years shows a significant negative effect of HbA1c on the PTH level. Mean calcium level among subjects with HbA1c ≤ 7% (53 mmol/mol) was 8.80 mg/dl compared with 8.94 mg/dl when HbA1c is ≥10% (86 mmol/mol) with no statistical difference. Although high FPG was associated with a lower PTH level, such association was not statistically significant. Conclusions Chronic hyperglycemia, as assessed by A1C level, is associated with a significantly attenuated PTH responsiveness to vitamin D deficiency without a significant change in calcium level. On the other hand, there was no significant association between FPG and PTH level.