Determinants of Orthostatic Hypotension in Type 2 Diabetes: Is Cardiac Autonomic Neuropathy the Main Factor?

ABSTRACT

OBJECTIVES: To evaluate the determinants of orthostatic hypotension (OH) in type 2 diabetes (T2D) and the usefulness of Δheart rate (HR)/Δsystolic blood pressure (SBP), index of cardiac baroreflex function, in identifying neurogenic OH. METHODS: In 208 participants with T2D, we diagnosed early cardiovascular autonomic neuropathy (CAN) and confirmed CAN according to 1 and 2 HR-based cardiovascular reflex tests (HR-CARTs). Through OH test we defined OH as SBP falls of ≥20 and ≥30 mm Hg with supine SBPs of <140 and ≥140 mm Hg, respectively. In participants with OH, we used the lying-to-standing and OH test and its diagnostic accuracy for neurogenic OH (as OH plus confirmed HR-CAN). RESULTS: OH was present in 25 participants and associated with lower HR-CART scores, higher glycosylated hemoglobin level, the presence of CAN, retinopathy, and peripheral vascular disease, the absence of hypertension, and physical activity (all, P < .05) but not with interfering drugs and ß-blockers. In a multiple logistic regression, HR-CAN was the main determinant of OH (odds ratio, 4.74) with physical activity and hypertension (odds ratios, 0.16 and 0.23; R2 = 0.22). ΔHR/ΔSBP had a good diagnostic accuracy for neurogenic OH (area under the receiver operating characteristic curve, 0.816 ± 0.087) and, at the cutoff of 0.5 bpm/mm Hg, a sensitivity of 100% and specificity of 63.2%. CONCLUSION: CAN remains the primary determinant of OH in T2D but does not explain all its variance. The index ΔHR/ΔSBP may represent a useful clinical tool to identify neurogenic OH.