Effect of vitamin D on stress-induced hyperglycaemia and insulin resistance in critically ill patients

L-carnitine supplementation ameliorates insulin resistance in critically ill acute stroke patients: a randomized, double-blinded, placebo-controlled clinical trial

Background and purpose

Insulin resistance (IR) can negatively affect clinical outcomes in acute ischemic stroke (IS) patients. Safe and cost-saving interventions are still needed to improve glycemic indices in this population. The primary objective was to evaluate L-carnitine (LC) effects in acute IS patients' homeostatic model assessment of IR (HOMA-IR).

Experimental approach

In this randomized, double-blind placebo-controlled clinical trial, critically ill IS patients were allocated to receive daily oral L-carnitine (1.5 g) or a placebo for six days. Fasting serum levels of glucose, insulin, C-reactive protein, LC, and HOMA-IR were measured on days 1 and 7. Mechanical ventilation duration, ICU/hospital duration, illness severity score, sepsis, and death events were assessed.

Findings/Results

Forty-eight patients were allocated to the research groups, 24 patients in each group, and all were included in the final analysis. LC administration showed a decrease in mean difference of HOMA-IR and insulin levels at day 7 compared to placebo, -0.94 ± 1.92 vs 0.87 ± 2.24 (P = 0.01) and -2.26 ± 6.81 vs 0.88 ± 4.95 (P = 0.03), respectively. However, LC administration did not result in significant improvement in clinical outcomes compared to placebo. The short duration of intervention and low sample size limited our results.

Conclusion and implication

Supplementation of L-carnitine improved HOMA-IR index in acute IS patients admitted to the critical care unit. Supplementation of LC would be a potential option to help to control IR in critically ill acute IS patients.

Efficacy of high-dose versus low-dose vitamin D supplementation on serum levels of inflammatory factors and mortality rate in severe traumatic brain injury patients: study protocol for a randomized placebo-controlled trial

Background

Traumatic brain injury (TBI) is the most common trauma worldwide and is a leading cause of injury-related death and disability. Inflammation is initiated as a result of the TBI, which is in association with severity of illness and mortality in brain trauma patients, especially in subdural hemorrhage and epidural hemorrhage cases. A high percentage of adults admitted to the intensive care unit with TBI are diagnosed with vitamin D deficiency; this deficiency may induce impaired immune responses and increase the risk of infections. Vitamin D intervention has been shown to modulate pro- and anti-inflammatory cytokines in non-critically ill patients, but to date, there is no substantial data on the effectiveness of vitamin D for the improvement of immune function in traumatic brain injury patients.

Methods/design

A randomized clinical trial (RCT) will be performed on 74 Iranian adults 18–65 years old with brain trauma and will be treated daily with vitamin D supplements (100,000 IU oral drop) or a similar placebo (1000 IU) for 5 days.

Discussion

If this randomized clinical trial demonstrates reductions in inflammatory cytokines, it would provide evidence for a multicenter clinical trial to evaluate the efficacy of vitamin D supplementation in neurocritically ill patients. Since vitamin D supplements are inexpensive and safe, this clinical trial could have the potential to improve clinical outcomes in traumatic brain injury patients through reduction of inflammation and infection-associated morbidity and mortality rates.

Trial registration

Iranian Registry of Clinical Trials, IRCT20180619040151N3. Registered on 10 August 2019.

Vitamin D in burn-injured patients

Recently, many studies have demonstrated pleotropic effects of vitamin D, including immune modulation and cardiovascular system activity. Sufficient vitamin D concentrations and supplementation of vitamin D may be of benefit in burn-injured patients. Low 25(OH)D has been observed in nearly all pediatric and most adult burn patients. Vitamin D has primarily been studied in pediatric burn patients, focusing on bone marker measurements and the incidence of fractures. The preferred vitamin D dose, formulation, and route of administration remain unknown, and there is limited data on the impact of vitamin D status on clinical outcomes. Further research should focus on determining optimal monitoring strategies, supplementation regimens and clinical outcomes like mortality, length of stay and incidence of sepsis.

Vitamin D and critical illness: what endocrinology can learn from intensive care and vice versa

The prevalence of vitamin D deficiency in intensive care units ranges typically between 40 and 70%. There are many reasons for being or becoming deficient in the ICU. Hepatic, parathyroid and renal dysfunction additionally increases the risk for developing vitamin D deficiency. Moreover, therapeutic interventions like fluid resuscitation, dialysis, surgery, extracorporeal membrane oxygenation, cardiopulmonary bypass and plasma exchange may significantly reduce vitamin D levels. Many observational studies have consistently shown an association between low vitamin D levels and poor clinical outcomes in critically ill adults and children, including excess mortality and morbidity such as acute kidney injury, acute respiratory failure, duration of mechanical ventilation and sepsis. It is biologically plausible that vitamin D deficiency is an important and modifiable contributor to poor prognosis during and after critical illness. Although vitamin D supplementation is inexpensive, simple and has an excellent safety profile, testing for and treating vitamin D deficiency is currently not routinely performed. Overall, less than 800 patients have been included in RCTs worldwide, but the available data suggest that high-dose vitamin D supplementation could be beneficial. Two large RCTs in Europe and the United States, together aiming to recruit >5000 patients, have started in 2017, and will greatly improve our knowledge in this field. This review aims to summarize current knowledge in this interdisciplinary topic and give an outlook on its highly dynamic future.

Effect of Magnesium Loading Dose on Insulin Resistance in Patients With Stress-Induced Hyperglycemia: A Randomized Clinical Trial

OBJECTIVES

There is currently no evidence that whether magnesium supplementation would improve stress-induced hyperglycemia (SIH) in critically ill patients. In this study, effects of magnesium loading dose on insulin resistance (IR) indices were evaluated in critically ill patients without diabetes having SIH.

METHODS

Seventy critically ill patients with SIH were assigned to receive a loading dose of magnesium (7.5 g of magnesium sulfate in 500 mL normal saline as intravenous infusion over an 8-hour period) or placebo. Changes in baseline of serum and intracellular magnesium and serum adiponectin (AD) levels, homeostasis model assessment of IR (HOMA-IR), and HOMA-AD ratio were assessed in this study.

RESULTS

Serum and intracellular magnesium levels increased significantly in patients in the magnesium group (P < .001). At day 3, there were significant differences between the magnesium group and the placebo group in the mean changes from baseline in the HOMA (between-group difference: -0.11; 95% confidence interval [CI]: -0.19 to -0.01; P = .02), the AD (between-group difference: 0.94; 95% CI: 0.41-1.48; P = .04), and the HOMA-AD ratio (between-group difference: -0.03; 95% CI: -0.04 to -0.01; P < .001).

CONCLUSION

In the present study, a single-loading dose of intravenous magnesium improved IR indices in critically ill patients with SIH.

Vitamin D status and its influence on outcomes following major burn injury and critical illness

Vitamin D deficiency is common among the general population. It is also observed in up to 76% of critically ill patients. Despite the high prevalence of hypovitaminosis D in critical illness, vitamin D is often overlooked by medical staff as the clinical implications and consequences of vitamin D deficiency in acute contexts remain to be fully understood. Vitamin D has a broad range of pleotropic effects on various processes and systems including the immune-inflammatory response. 1α,25-dihydroxyvitamin D (1,25(OH)₂D), has been shown to promote a tolerogenic immune response limiting deleterious inflammatory effects, modulation of the innate immune system, and enhancement of anti-microbial peptides. Vitamin D deficiency is frequently observed in critically ill patients and has been related to extrinsic causes (i.e., limited sunlight exposure), magnitude of injury/illness, or the treatment started by medical doctors including fluid resuscitation. Low levels of vitamin D in critically ill patients have been associated with sepsis, organ failure, and mortality. Despite this, there are subpopulations of critical illness, such as burn patients, where the literature regarding vitamin D status and its influence on outcomes remain insufficient. Thermal injury results in damage to both burned and non-burned tissues, as well as induces an exaggerated and persistent immune-inflammatory and hypermetabolic response. In this review, we propose potential mechanisms in which burn injury affects the vitamin D status and summarizes current literature investigating the influence of vitamin D status on outcomes. In addition, we reviewed the literature and trials investigating vitamin D supplementation in critically ill patients and discuss the therapeutic potential of vitamin D supplementation in burn and critically ill patients. We also highlight current limitations of studies that have investigated vitamin D status and supplementation in critical illness. Thermal injury influences vitamin D status. More studies investigating vitamin D depletion in burn patients and its influence on prognosis, via standardized methodology, are required to reach definitive conclusions and influence clinical practice.

High glucose induces O-GlcNAc glycosylation of the vitamin D receptor (VDR) in THP1 cells and in human macrophages derived from monocytes

Chronic hyperglycemia increases the carbon flux through the hexosamine pathway, allowing the accumulation of UDP-GlcNAc. UDP-GlcNAc is the sugar donor for the enzyme-mediated protein glycosylation event known as OGlcNAcylation. This posttranslational modification targets several transcription factors implicated in glucose toxicity, insulin resistance, and diabetes. Vitamin D plays an important role in glucose homeostasis and insulin secretion through transcriptional mechanisms mediated by its receptor (VDR). Vitamin D deficiency has been associated with higher susceptibility to bacterial diseases in diabetic patients. However, it has not been explored whether VDR is subject to OGlcNAcylation or whether high glucose affects its transcriptional or biological activities. The aim of this study was to evaluate the effect of hyperglycemia on VDR OGlcNAcylation and its effects on vitamin D-mediated transcription. We predicted potential OGlcNAcylation sites using free software. Our results showed that hyperglycemia (30 mM) induces the OGlcNAcylation of VDR in THP1 cells and in human macrophages derived from monocytes (MDM). This condition did not hamper the vitamin D-dependent activation of LL-37 gene expression, and even did not impair the macrophage bactericidal activity. Our study provides new insight into vitamin D receptor posttranslational modification that may have relevance on the physiological responses of long-term hyperglycemia.