Effect of Vitamin D on Stress-induced Hyperglycaemia and Insulin Resistance in Critically Ill Patients

N. Alizadeh; H. Khalili; M. Mohammadi; A. Abdollahi; S. Ala

Disclosures

Int J Clin Pract. 2016;70(5):396-405. 

In This Article

Abstract and Introduction

Abstract

Aim: Effects of vitamin D supplementation on the glycaemic indices and insulin resistance in diabetic and non-diabetic patients were studied. In this study, effects of vitamin D supplementation on stress-induced hyperglycaemia and insulin resistance were evaluated in non-diabetic surgical critically ill patients.

Methods: Adult surgical patients with stress-induced hyperglycaemia within the first 24 h of admission to the ICU were recruited. The patients randomly assigned to receive either vitamin D or placebo. Patients in the vitamin D group received a single dose of 600,000 IU vitamin D3 as intramuscular injection at time of recruitment. Besides demographic and clinical characteristics of the patients, plasma glucose, insulin, 25(OH) D and adiponectin levels were measured at the time of ICU admission and day 7. Homoeostasis model assessment for insulin resistance (HOMA-IR) and homestasis model assessment adiponectin (HOMA-AD) ratio were considered at the times of assessment.

Results: Comparing with the baseline, plasma 25(OH) D level significantly increased in the subjects who received vitamin D (p = 0.04). Improvement in fasting plasma glucose levels was detected in day 7 of the study compared with the baseline status in both groups. HOMA-IR showed a decrement pattern in vitamin D group (p = 0.09). Fasting plasma adiponectin levels increased significantly in the vitamin D group (p = 0.007), but not in the placebo group (p = 0.38). Finally, changes in HOMA-AD ratio were not significant in the both groups.

Conclusion: Vitamin D supplementation showed positive effect on plasma adiponectin level, as a biomarker of insulin sensitivity in surgical critically ill patients with stress-induced hyperglycaemia. However, effects of vitamin D supplementation on HOMA-IR and HOMA-AD as indicators of insulin resistance were not significant.

Introduction

Hyperglycaemia during acute illnesses is common and associated with several adverse clinical outcomes.[1–4] Stress-induced hyperglycaemia (SIH), is the term that reflects insulin resistance and glucose intolerance in severely ill patients, in the absence of a pre-existing diabetes mellitus.[5] There is no consensus definition for the blood glucose threshold of SIH.

The American Diabetes Association and American Association of Clinical Endocrinologists is defined SIH as any blood glucose concentration > 140 mg/dl (7.8 mmol/l) in hospitalised patients without evidence of previous diabetes mellitus.[6] However in some clinical studies, SIH was considered as any blood glucose > 110 mg/dl.[7–9] Considering different blood glucose thresholds for SIH, 30–97.5% of critically ill patients experienced SIH at the time of ICU admission.[7,10] The exact pathophysiology of SIH in acute illnesses is not fully described.[11,12]

During acute illnesses release of counter-regulatory hormones including catecholamines, cortisol, glucagon and growth hormone as well as pro-inflammatory cytokines such as interleukin-1 (IL-1), IL-6 and tumour necrosis factor α (TNF-α), leads to rapid glycogenolysis, gluconeogenesis and insulin resistance.[13–15]

Tight control of blood glucose is a challenging issue in critically ill patients.[16] Intensive insulin therapy resulted in an unfavourable increase in the incidence of hypoglycaemia.[16–18] Considering pathophysiology of SIH, reversing of inflammatory cascades and improving insulin resistance may be effective strategies for control of SIH in critically ill patients.[19]

Role of vitamin D deficiency in pathogenesis of type 2 diabetes mellitus and insulin resistance has been recently described.[20] Different mechanisms including increase in expression of insulin receptors and regulation of glucose transport,[21] glucose uptake in adipocytes and also decreasing the activity of glucose transporter-4,[22,23] have been proposed for explaining the role of vitamin D in improvement of insulin resistance.

Effects of vitamin D supplementation on the glycaemic indices and insulin resistance in diabetic and non-diabetic patients were studied. Some of these studies showed positive effects of vitamin D supplementation in modifying fasting glucose, HbA1C or insulin resistance[24–28] while some others could not confirm the findings.[29–31]

To the best of our knowledge, effects of vitamin D supplementation on SIH and insulin resistance have not been evaluated in critically ill patients. In this study, effects of vitamin D supplementation on SIH and insulin resistance were evaluated in non-diabetic surgical critically ill patients.

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