Type 2 Diabetes Mellitus and Functional Hypoparathyroidism

ABSTRACT

Purpose: The present study aims to investigate the effect of blood sugar regulation and vitamin D levels on calcium metabolism and parathormone levels in patients with type 2 diabetes mellitus.
Material and Method: We included 132 patients with type 2 diabetes mellitus who presented to our outpatient clinic for regular check up between August 2013 and October 2013. Fasting blood glucose, HbA1c, calcium, phosphorus, magnesium, albumin, creatinine, parathormone, 25-Hydroxy vitamin D [25(OH)D], spot urinary calcium and creatinine levels were studied for each patient.
Results: Vitamin D levels were below 30 ng/mL in 96.9% (n=128) and below 20 ng/mL in 78.7% (n=102) of the patients included in the study. Patients with impaired blood sugar regulation (HbA1c >10%) had lower levels of PTH, albumin and 25(OH)D levels and higher phosphorus levels compared to patients with HbA1c levels below 10% (p=0.018, p=0.043, p=0.002, p=0.01, respectively). The rates of functional hypoparathyroidism (parathormone <65 ng/mL) in patients with vitamin D levels below 30 ng/mL and 20 ng/mL were 63.2% and 59.6%, respectively. Among the diabetic patients with vitamin D levels <30 ng/mL, magnesium levels were significantly lower in those with functional hypoparathyroidism (parathormone <65 ng/mL) compared to those with secondary hyperparathyroidism (p=0.015). Comparative statistical analysis of patients with HbA1c levels above and below 10% demonstrated higher proportion of patients with functional hypoparathyroidism in the group with impaired blood sugar regulation (p=0.035 for patients with vitamin levels below 30 ng/mL, and p=0.031 for patients with vitamin levels below 20 ng/mL).
Discussion: Impaired blood sugar regulation leads to functional hypoparathyroidism with secondary hypomagnesemia in type 2 diabetes mellitus, as was previously described for subjects with type 1 diabetes mellitus.