Adipose tissue inflammatory markers may signal cardiac risk in diabetes
MedWire News: Cardiac autonomic imbalance is associated with adipose tissue-derived inflammation in early Type 2 diabetes, occurring alongside alterations in adiponectin, leptin, and interleukin (IL)-6, research shows.
The authors say their data supports studies suggesting that factors related to autonomic dysfunction may be better predictors of cardiac events than more traditional risk factors, which fail to predict silent ischemia in 40% of patients.
As reported in the journal Experimental Diabetes Research, David Lieb (Eastern Virginia Medical School, Virginia, USA) and team recruited 15 individuals to the following groups: healthy controls with no prior history of diabetes, individuals with newly diagnosed diabetes, and those with established diabetes.
The authors obtained anthropormorphic and biochemical measurements for each participant and assessed cardiac autonomic function by measuring and analyzing heart rate variability (HRV).
They used time-domain analysis of HRV to measure and record sympathetic and parasympathetic control of heart beat (R-R interval on the electrocardiogram) with different maneuvers such as deep breathing, the Valsalva maneuver, and standing up from the supine position.
They found that patients with newly diagnosed and established diabetes had lower HRV with deep breathing than the healthy controls, with R-R ratios of 1.20 and 1.17 versus 1.26.
And established diabetics had a significantly lower Valsalva ratio compared with the newly diagnosed diabetics and controls (R-R ratios of 1.24 vs 1.37 and 1.58).
They also found that IL-6 was significantly higher in the diabetic groups (newly diagnosed and established) compared with the control (11.6 pg/ml and 12.0 pg/ml vs 2.8).
In addition, total adiponectin-to-leptin ratio (TA/L) was significantly higher in the established diabetics compared with the newly diagnosed diabetics and controls (0.53 vs 0.24 and 1.17).
Interestingly, a Spearman's rank correlation test revealed that IL-6 correlated negatively with the standard deviation of all normal R-R intervals.
"This suggests an association between IL-6 and abnormalities in both the measure of sympathetic and parasympathetic components of the reduced HRV seen in patients with diabetes," say the authors.
Also, TA/L ratio correlated positively with total spectral power, indicating, they say, that the balance of adinopectin and leptin may be related to autonomic function.
"A better understanding of the autonomic dysfunction and adipose tissue inflammation seen in early Type 2 diabetes will lead to further measures for determining which individuals are at the highest risk for cardiovascular disease and mortality, and also to the development of new therapies for reducing that risk," conclude Lieb and team.
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By Sally Robertson