Health & body · 2001
Do changes in blood track changes in the nervous system balance regulating the heart in people with type 2 diabetes?
Yes—in 30 patients without diabetic neuropathy, changes in plasma free fatty acids tracked changes in the LF/HF ratio, a measure used to assess cardiac sympathetic/parasympathetic balance. The association appeared during lipid infusion and after 3 months of improved metabolic control with intensified insulin treatment.
Details
Decreased heart rate variability (HRV) is a risk factor for cardiovascular mortality. Elevated plasma free fatty acid (FFA) levels decrease HRV in healthy subjects. The researchers therefore investigated how changes in plasma FFA levels affect HRV in patients with non-insulin-dependent diabetes (NIDDM).
Thirty NIDDM patients without diabetic neuropathy volunteered for a two-phase intervention study. In study A, researchers examined changes in HRV during an infusion of 10% lipid emulsion plus heparin (n = 15) or a saline infusion serving as the control (n = 15). In study B, all 30 patients had HRV measured again after 3 months of improved metabolic control achieved through intensified insulin treatment.
In study A, lipid emulsion infusion increased plasma FFA (P < 0.001), catecholamine concentrations (P < 0.005), mean arterial blood pressure (P < 0.005), and the low-frequency/high-frequency (LF/HF) ratio of HRV (P < 0.001). Changes in plasma FFA correlated with changes in the LF/HF ratio (r = 0.57; P < 0.02). During saline infusion, metabolic and cardiovascular parameters remained unchanged throughout the test.
In study B, improved metabolic control lowered fasting plasma glucose (P < 0.005), FFA (P < 0.001), norepinephrine (P < 0.02), epinephrine (P < 0.04), glycosylated hemoglobin (P < 0.001), mean arterial blood pressure (P < 0.05), and the LF/HF ratio (P < 0.001). The percentage decline in plasma FFA correlated with the percentage change in the LF/HF ratio (r = 0.72; P < 0.001).
In a multivariate analysis, percentage changes in the LF/HF ratio were associated with percentage changes in plasma FFA independently of gender and percentage changes in body mass index, waist/hip ratio, plasma norepinephrine, epinephrine, glycosylated hemoglobin, and daily insulin therapy.
The researchers concluded that changes in plasma FFA levels may have a parallel effect on the balance between cardiac sympathetic and parasympathetic nervous system activity in NIDDM patients.
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