Background Diabetic autonomic neuropathy can be associated with abnormalities in diurnal blood pressure rhythm. It has been suggested that carnitine deficiency can be involved in the development of both diabetic neuropathy and insulin resistance. The aim of the study was to assess serum carnitine levels and diurnal blood pressure rhythm in obese type 2 diabetic subjects with subclinical autonomic neuropathy and without neuropathy and to determine influence of L-carnitine supplementation on autonomic neuropathy and blood pressure rhythm.
Material and methods Study was performed in 30 obese type 2 diabetic patients treated with oral antidiabetic agents. Subclinical autonomic neuropathy of cardiovascular system was present in 15 of them - group NA(+) and was not found in 15 others - group NA(-). Control group consisted of 15 obese, nondiabetic subjects. In all subjects body mass index (BMI), waist-hip ratio (WHR), fasting serum free and total carnitine, glucose, insulin, C-peptide, lipids and HbA1c were measured. Assessment of autonomic neuropathy was based on a Ewing’s battery of autonomic function tests. Ambulatory blood pressure monitoring was performed with SpaceLabs 90207. Investigation was performed twice, before and after supplementation of 1000 mg L-carnitine per day, given orally for 3 month.
Results No differences in age, sex, BMI and WHR was found in all investigated groups. Diurnal blood pressure rhythm and number of subjects with normal night blood pressure fall was similar in NA(-) and NA(+) patients. Similar levels of free and total carnitine, glucose, insulin, C-peptide, HbA1c, total cholesterol, LDL, HDL cholesterol and triglicerides were found in NA(+) and NA(-) groups. After supplementation of L-carnitine in diabetic patients, serum carnitine levels increased but there was no change in BMI, autonomic nervous system function and blood pressure rhythm.
Conclusions Subclinical autonomic neuropathy in obese type 2 diabetic subjects is not associated with serum carnitine concentration and abnormalities in blood pressure rhythm. Supplementation of L-carnitine does not influence the autonomic neuropathy and diurnal blood pressure rhythm.