News in medicine : Association of Diabetes and Glycated Hemoglobin With the Risk of Intracerebral Hemorrhage
Written by David Spence BA, MBA, MD, FRCPC, FAHA
This study reports a J curve for A1c and intracerebral hemorrhage. Although diabetes is known to increase the risk of stroke, particularly strokes related to small-vessel disease and intracranial stenosis, it seems likely that, in this case, the A1c may be a surrogate for medical care in general and blood pressure control in particular. Although the authors adjusted for hypertension, 70% of their diabetic patients were hypertensive, and it seems they did not/could not adjust for blood pressures preceding the intracerebral hemorrhages. Strict blood pressure control virtually eliminates the risk of hypertensive intracerebral hemorrhage. In the North American Symptomatic Carotid Endarterectomy Trial,1 with strenuous efforts to control blood pressure, intracranial hemorrhages (including lobar and subarachnoid bleeds, which are not due to hypertension) were reduced to 0.5% of strokes, at a time when approximately 20% of strokes were hemorrhagic.
The J curve might be due to hemorrhagic conversion of infarctions. Patients with a pulse pressure >60 and a diastolic pressure <60 have a 5.85-fold risk of stroke, explained by the mainly diastolic blood flow of the brain and heart, the large pressure gradient in cerebral arteries, and the increased likelihood of a cuff artifact in measurement of blood pressure.2
1.Barnett HJ, Taylor DW, Eliasziw M, et al. Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators. N Engl J Med. 1998;339(20):1415-1425. https://www.nejm.org/doi/10.1056/NEJM199811123392002
2.Spence JD. Systolic blood pressure targets, diastolic J curve and cuff artefact in blood pressure measurement: a note of caution. Eur J Neurol. 2017;24(11):1323-1325. https://onlinelibrary.wiley.com/doi/abs/10.1111/ene.13442.