The effect of adipokines on insulin sensitivity in critically ill patients

Journal of Endocrinology, Metabolism and Diabetes of South Africa, June, 2007 by U. Wilgen, S. Omar, N. Crowther, J. Paiker

Objectives: To determine if the adipokines TNF[alpha], IL-6 and adiponectin are significant determinants of insulin sensitivity in critically ill patients.

Methods: A prospective observational study was performed. Forty sequential admissions to the Chris Hani Baragwanath ICU were recruited. Adiponectin, TNF[alpha] and IL-6 levels were measured on admission, day 3, day 7 and on discharge from the ICU. Severity of illness using the APACHE II score was calculated on admission. Blood glucose was measured 2 - 4-hourly, and a mean concentration calculated over the 24 hours. Insulin infusions were started when the blood glucose values exceeded 6.0 mmol/l, and adjusted according to a fixed sliding scale. Other factors related to insulin sensitivity such as cortisol, cholesterol and triglycerides were also measured.

Results: Although there was no statistically significant change in the mean 24-hour glucose concentration throughout the duration in ICU, the amount of administered insulin required to maintain normoglycaemia changed dramatically. To correct for this, a ratio of the administered insulin: mean plasma glucose was calculated and used as a measure of insulin sensitivity.

Adiponectin levels increased significantly from admission to discharge. IL-6 levels decreased significantly. TNF[alpha] levels did not change significantly. No statistically significant correlations were found between the levels of adiponectin, TNF[alpha] or IL-6 and insulin sensitivity. There was no significant correlation between APACHE II score and insulin sensitivity. Serum triglycerides and total cholesterol showed significant differences from admission to discharge, with values increasing from admission levels. This was inversely related to serum cortisol and IL-6 levels, and directly related with adiponectin levels.

Conclusions: Evidence of decreased insulin sensitivity during the stay in ICU was demonstrated. However, there was no statistically significant association between the adipokines adiponectin, TNF[alpha] or IL-6 and insulin sensitivity. Furthermore, other factors which may influence insulin sensitivity such as cortisol cholesterol and triglycerides did not appear to play a significant role. Insulin sensitivity is affected by multiple factors, and further research into its aetiology is required.

U Wilgen *, S Omar (#), N Crowther *, J Paiker *

* Department of Chemical Pathology, Johannesburg Hospital, NHLS, University of the Witwatersrand; (#) Department of Critical Care, Chris Hani Baragwanath Hospital, University of the Witwatersrand