This study examined the effect of glucose ingestion on cardiac autonomic function in non-obese women and obese women with and without type 2 diabetes. Heart rate variability (HRV) was measured via continuous ECG and beat-by-beat blood pressure was recorded with finger photoplethysmography (Portapress) in a fasted state and in response to a 75 g glucose load in 42 middle-aged women (40-60 yr). Upright tilt was also utilized as an orthostatic stress to provide a clinically relevant challenge to the cardiovascular system. Significant main effects for log transformed (Ln) total power (TP, msec 2 ) were observed with upright tilt (P<0.01) and glucose challenge (P<0.05). LnTP decreased in all groups in both the fasted and fed state with upright tilt (P<0.01), but glucose ingestion resulted in higher LnTP in the supine position only (P=0.008). Tilt resulted in a significant main effect for low frequency (LFnu, normalized units) and high frequency (Hfnu) power (P<0.000), while the glucose challenge had no effect on LFnu or HFnu power. LFnu approached significance for group differences (P=0.07), such that the non-obese had lower LF power than either of the obese groups. Sympathovagal balance (LnLF/HF ratio) was affected by position (P<0.000) and group (P<0.05), with a lower LnLF/HF in the non-obese than in the obese women. Baroreceptor sensitivity decreased (P<0.01) during upright tilt but was not changed by the glucose challenge. In conclusion, basal sympathovagal balance is higher in obese individuals with and without type 2 diabetes. Women with type 2 diabetes showed no differences in autonomic function with an orthostatic challenge or glucose load than non-diabetic, obese women. The glucose load did alter total spectral power in all of these middle-aged women, but had no impact on baroreceptor sensitivity.Jill Kanaley, PhD, 820 Comstock Ave, Rm 201, Syracuse, NY 13244, 315-443-9698 phone, 315-443-9375 fax Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers