Cytokines, Type 2 DM and the Metabolic Syndrome

Inflammatory markers have been widely implicated in Diabetes Mellitus (DM) and the metabolic syndrome (Mets). Data on the association of cytokines (pro inflammatory mediators) and components of the Mets are sparse in sub Saharan Africa.

We sought to document the pattern of distribution of cytokines in Nigerian subjects with type 2 DM and compare cytokine levels between DM subjects with and without the Mets.

200 subjects with type 2 DM and 100 healthy sex and aged matched Controls were studied. Anthropometric indices, lipid parameters and cytokine levels, which included interleukin 10 (IL-10), tumour necrosis factor-alpha (TNF-α), interferon gamma (IFN-γ) and C reactive protein (CRP) were determined. Continuous variables were compared between subjects with type 2 DM and the controls and also between DM subjects with and without the Mets.

The mean levels of all studied cytokines were significantly higher in the subjects with type 2 DM than the Control subjects, save for IFN-γ which was significantly lower in type 2 DM. The mean cytokine levels were comparable in the DM subjects with and without the Mets and also comparable in obese DM and non obese DM subjects. Of the Mets defining criteria, waist circumference (WC) and Triglyceride (TG) were found to be significantly associated with only two of the studied cytokines. The correlation coefficient and p values of these findings are as follows: WC vs TNF-α (r = 0.16, p = 0.001) and TG vs CRP (r = 0.15, p = 0.03). Multiple regression analyses showed that the cytokines were linearly associated with each other but not with other clinical and biochemical variables. The cytokines were found to be interrelated. IL-10 with a beta value of 0.14 predicted the presence of INF-γ with a 95% confidence interval of 0.000 - 0.109 and a p value of 0.05. TNF-α with a beta value of 0.17 predicted the presence of IL-10 with a 95% confidence interval of 0.004 - 0.034 and a p value of 0.01. IL-10 with a beta value of 0.17 predicted the presence of TNF-α with a 95% confidence interval of 0.3-0.590 and a p value of 0.01.

Cytokine levels are higher in DM than non DM subjects; however, the cytokine levels are not strongly associated with the Mets. Limited correlations were found between each of the cytokines and the parameters of the Mets. Further studies on this entity amongst Africans should be carried out to ascertain if these results are peculiar to DM subjects in sub- Saharan Africa.