The Frequency of Vitamin D Deficiency in Obese Patients on Bariatric Surgery Wait List: Is there any Association with Co-existence of Prediabetes or Diabetes?

ABSTRACT

Objective: The impact of co-existence of prediabetes on 25 (OH)D3 deficiency is less known. We investigated the prevalence and predictors of 25(OH)D3 deficiency in obese adults on the bariatric surgery waitlist.

Material and Methods: One hundred ninety-nine patients without known chronic diseases including diabetesmellitus (DM) and hypertension were included. Anthropometric, biochemical, and hormonal [fasting insulin, C-peptide, 25(OH)D3] parameters were analyzed. Insulin resistance (IR) was calculated using the homeostasis model assessment of IR (HOMA-IR). Patients having HOMA-IR of ≥2.5 were considered insulin resistant. Patients were divided into subgroups according to body mass index (BMI), fasting blood glucose, HOMA-IR, glycated hemoglobin A1c (HbA1c), and 25(OH)D3 levels.

Results: According to HbA1c levels, prediabetes and DM were diagnosed in 39.6% (n=79) and 27.1% (n=54) of patients. The 25(OH)D3 levels were severely deficient, deficient, and insufficient in 47.2%, 36.7%, and 10.6%of patients; however, the levels were sufficient (≥30 ng/mL) only in 5.5%. The mean 25(OH)D3 level was 9.59, 9.76, and 12.08 ng/mL in nondiabetic, prediabetic, and diabetic patients (p>0.05). BMI and 25(OH)D3 levels were negatively correlated (p=0.045, r=-0.142). HOMA-IR was not correlated with 25(OH)D3 levels (p=0.98); it was similar in patients with different 25(OH)D3 levels. Age ≥40 years andmale gender were significant predictors for severe 25(OH)D3 deficiency, but IR, prediabetes, and DM were not significant predictors.

Conclusion: Increased BMI was associated with decreased 25(OH)D3 levels. The co-existence of prediabetes does not seem to affect 25(OH)D3 levels. Age ≥40 years and male gender were significant predictors for severe 25(OH)D3 deficiency. Severe 25(OH)D3 deficiency was frequent in obese patients on the bariatric surgery waitlist. Vitamin D deficiency was also shown in other studies on obesity. 25(OH)D3 levels should be measured in all patients undergoing bariatric surgery and managed accordingly. The effect of preoperative vitamin D replacement on postoperative weight loss will clarify the association between vitamin D levels and obesity.