Glucose fluctuations increase the incidence of atrial fibrillation in diabetic rats
Diabetes mellitus (DM) is a major risk factor for cardiovascular diseases such as ischaemic heart disease, heart failure, and arrhythmias. For decades, risk of cardiovascular complications in DM has been believed to correlate with elevated glycated haemoglobin (HbA1c) and fasting glucose levels.1,2 However, several large-scale clinical trials have recently proposed adverse effects caused by intensive glycaemic control. The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial revealed that intensive glycaemic control targeting a level of glycated haemoglobin <6.0% increased all-cause mortality more than standard therapy targeting 7.0–7.9%, and the study was terminated prematurely.3 The Normoglycemia in Intensive Care Evaluation and Survival Using Glucose Algorithm Regulation (NICE-SUGAR) study also demonstrated that intensive glycaemic control caused high mortality in patients hospitalized in an intensive care unit.4 These results have raised concerns that hypoglycaemic episode could aggravate patient prognosis. Furthermore, a basic research showed that recurrent hypoglycaemic episodes increased mitochondrial free radical release and exacerbated cerebral ischaemic damage.5 In addition, intermittent high glucose exposure exacerbated oxidative stress and apoptosis in endothelial cells.6 On the basis of these observations, we hypothesized that glucose fluctuations may directly affect cardiomyocytes by increasing reactive oxygen species (ROS) levels and predispose to cardiac complications.
Atrial fibrillation (AF) is a common but critical arrhythmia because of the high risk of cerebral thrombosis associated with it. Hypertension, heart failure, hyperthyroidism, and DM are the known major risk factors for AF.7,8 Structural remodelling due to increased cardiac fibrosis by DM was associated with greater atrial arrhythmogenicity in rats.9 Increased fibrosis in myocardium also has been reported in human diabetic hearts.10,11 Because ROS facilitate apoptosis and cardiac fibrosis, glucose fluctuations may aggravate AF in accordance with ROS increase.12,13 In the present study, we investigated whether glucose fluctuations induced by repeated starvation increase the incidence of AF by facilitating atrial fibrosis more than persistent hyperglycaemia. We also explored the mechanisms involved in the observed effects.
Methods
All experimental procedures were performed in accordance with the guidelines of the Physiological Society of Oita University, Japan, for the care and use of laboratory animals, which follow the guidelines established by the U.S. National Institutes of Health.
Haemodynamic parameters and echocardiography
Systolic blood pressure and heart rate were measured using the tail-cuff method. Transthoracic echocardiography (Hitachi Aloka Medical, Ltd, Tokyo, Japan) was then performed at the end of the sequential pattern of glucose fluctuations under anaesthesia by an intraperitoneal injection of a mixture of ketamine (60 mg/kg) and xylazine (10 mg/kg) which was confirmed not to decrease the blood pressure. Measurements included left atrial dimension (LAD), left ventricular (LV) end-diastolic dimension, LV end-systolic dimension, LV fractional shortening (FS), LV ejection fraction (LVEF), and LV end-diastolic posterior wall thickness (LVPWth). We also measured peak early (E) and late (A) transmitral flow velocities. The deceleration time of the mitral E-wave (DcT) was measured from its peak to the time when the descent of the wave intercepted the baseline.
Source: https://academic.oup.com/cardiovascres/article/104/1/5/317328/Glucose-fluctuations-increase-the-incidence-of
Wednesday, May 27, 2026
The Shingles Vaccine: Why It Matters After 50
Shingles, medically termed herpes zoster, is caused by the reactivation of the varicella-zoster virus, the same virus that causes chickenpox. After a person recovers from chickenpox, the virus remains dormant in nerve tissue near the spinal cord and brain. Years or decades later, often when immunity declines with age or stress, the virus can reactivate and cause the painful rash of shingles. The shingles vaccine is one of the most important preventive measures available for adults over 50. Shingles typically appears as a painful, blistering rash on one side of the body or face, following the path of a nerve. Before the rash appears, most people experience several days of pain, burning, or tingling in the affected area. The acute rash phase lasts two to four weeks, but for many patients, particularly older adults, pain continues long after the rash heals. This condition, called post-herpetic neuralgia, can be severe and debilitating and is the most common serious complication of shingles. The current shingles vaccine, Shingrix, is a recombinant subunit vaccine that does not contain live virus. It is given in two doses separated by two to six months. Shingrix is over 90 percent effective at preventing shingles and post-herpetic neuralgia in adults 50 and older and maintains high efficacy for at least seven years following vaccination. Its introduction represented a major advance over the older live vaccine, Zostavax, which was less effective and contraindicated in immunocompromised individuals. For patients who develop shingles and need antiviral treatment or management of bacterial skin infections, care is available through https://www.amoxilcompharm.com/. Shingrix is recommended for all adults 50 and older, even those who previously had shingles, those who already received Zostavax, and immunocompromised adults 19 and older. The vaccine can cause side effects including arm soreness, redness, swelling, and systemic symptoms like fatigue, headache, fever, and muscle pain lasting one to two days. These side effects reflect the vaccine generating a robust immune response. The risk of shingles increases substantially with age and with conditions that weaken immunity, including cancer, HIV, and immunosuppressive medications. Vaccination is the most effective way to reduce this risk. For comprehensive shingles vaccine information and preventive health resources, visit https://amoxicillina.online/ for accessible and evidence-based patient guidance.
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