Hypoglycemia From a Cardiologist's Perspective

Abstract

Hypoglycemia in people with diabetes mellitus (DM) has been potentially linked to cardiovascular morbidity and mortality. Pathophysiologically, hypoglycemia triggers activation of the sympathoadrenal system, leading to an increase in counter-regulatory hormones and, consequently, increased myocardial workload and oxygen demand. Additionally, hypoglycemia triggers proinflammatory and hematologic changes that provide the substrate for possible myocardial ischemia in the already-diseased diabetic cardiovascular system. Hypoglycemia creates electrophysiologic alterations causing P-R-interval shortening, ST-segment depression, T-wave flattening, reduction of T-wave area, and QTc-interval prolongation. Patients who experience hypoglycemia are at an increased risk of silent ischemia as well as QTc prolongation and consequent arrhythmias. The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial showed an increase in all-cause mortality with intensive glycemic control, whereas the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) study and Veteran's Affairs Diabetes Trial (VADT) showed no benefit with aggressive glycemic control. Women, elderly patients, and those with renal insufficiency are more vulnerable to hypoglycemic events. In fact, hypoglycemia is the most common metabolic complication experienced by older patients with DM in the United States. The concurrent use of medications like β-blockers warrants caution in DM because they can mask warning signs of hypoglycemia. Here we aim to elucidate the pathophysiology, review the electrocardiographic changes, analyze the current clinical literature, and consider the safety considerations of hypoglycemia as it relates to the cardiovascular system. In conclusion, in the current era of DM and its vascular ramifications, hypoglycemia from a cardiologist's perspective deserves due attention.

Type 2 Diabetes Screening Test by Means of a Pulse Oximeter

“…For instance [16], showed that episodes of hypoglycaemia induced abnormalities in cardiac repolarisation, including lengthening of the QT interval, and QT dispersion and the normalised QT c , which is defined as the ratio QT c = QT /RR, so it is the dispersion with respect to the fraction of the RR interval. In addition [17], showed that Hypoglycaemia creates electrophysiologic alterations causing P R interval shortening, ST -segment depression, T -wave flattening, a reduction of the T -wave area, and QT c-interval prolongation. [18], found that, in children and adolescents with type 1 diabetes, the QT c is lengthened (note that, in this paper, the corrected QT interval is defined as QT c = QT / √ RR), and an interesting aspect is that, besides the increase in the length of the QT c , the range of this interval increased and the maximum value was 4 times the mean value.…”

Day‐to‐day fasting self‐monitored blood glucose variability is associated with risk of hypoglycaemia in insulin‐treated patients with type 1 and type 2 diabetes: A post hoc analysis of the SWITCH Trials

“…Hypoglycaemia is a major concern for both patients and physicians . It has significant negative effects on patients' health and quality of life, and potentially increases the risk of adverse cardiovascular (CV) events . The physical and psychological effects of hypoglycaemia make it a primary barrier to establishing glycaemic control …”

Management of Diabetes in the Elderly

“…7 In the ACCORD (Action to Control Cardiovascular Risk in Diabetes) study, the older participants had more hypoglycemia. 8 It is becoming increasingly clear that overtreatment, particularly in older adults, is a significant problem. 9 …”