Does the autonomic nervous system play a role in the development of insulin resistance? A study on heart rate variability in first-degree relatives of Type 2 diabetes patients and control subjects.
OBJECTIVE
To investigate dysregulation of the autonomic nervous system as a potential mechanism for early insulin resistance in the development of Type 2 diabetes.


METHODS
Thirteen healthy individuals with first-degree relatives with Type 2 diabetes (R) were compared with 14 control subjects without family history of diabetes (C), matched for age, body mass index and sex. An oral glucose tolerance test and a hyperinsulinaemic euglycaemic clamp were performed. Analysis of heart rate variability during rest, controlled breathing, an orthostatic manoeuvre and a standardized physical stress (cold pressor test (CPT)), were used to evaluate the activity of the autonomic nervous system.


RESULTS
Fasting blood glucose, HbA1c and serum insulin were similar in the R and C groups. The M-value, reflecting insulin sensitivity, did not differ significantly between the groups. Total spectral power and high-frequency power were lower in R during controlled breathing (P = 0.05 and P = 0.07, respectively), otherwise there were no significant differences between R and C in heart rate variability. However, low-frequency (LF)/high-frequency (HF) spectral power ratio during CPT, reflecting sympathetic/parasympathetic balance, was negatively associated with insulin sensitivity (r = -0.53, P = 0.006). When all subjects were divided into two groups by the mean M-value, the low M-value group displayed an overall higher LF/HF ratio (P = 0.04). HF power was lower in the low M-value group during controlled breathing and CPT (P = 0.01 and P = 0.03, respectively).


CONCLUSIONS
An altered balance of the parasympathetic and sympathetic nervous activity, mainly explained by an attenuated parasympathetic activity, might contribute to the development of insulin resistance and Type 2 diabetes.
Lindmark
S
S
Department of Medicine, Umeå University Hospital, Umeå, Sweden.
Wiklund
U
U
Bjerle
P
P
Eriksson
J W
JW
D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000235:genetics; D001342:Autonomic Nervous System Diseases / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D001835:Body Weight; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000503:physiopathology*; D005260:Female; D015309:Glucose Clamp Technique / Q000379:methods; D005951:Glucose Tolerance Test / Q000379:methods; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D010375:Pedigree
D001786:Blood Glucose; D006442:Glycated Hemoglobin