The finding, published in the current online issue of Diabetes Care, challenges the conventional wisdom that hypoglycemia is primarily a problem among diabetic patients with well-controlled diabetes (who have low average blood-sugar levels).
Low blood sugar, or hypoglycemia, can cause unpleasant symptoms but is typically treatable with food or a sweet drink. Severe hypoglycemia occurs when blood sugar gets so low a patient needs assistance, and may result in dizziness or mental confusion, injury, car accident, coma or, rarely, even death. Several recent studies have found that patients who experienced severe hypoglycemia were also at higher risk for dementia, falls, fractures and heart attacks, compared with patients who did not experience hypoglycemia.
“Many clinicians may assume that hypoglycemia is not much of a problem in poorly controlled type 2 diabetes given their high average blood-sugar levels,” said senior author and study principal investigator, Andrew Karter, PhD, of the Kaiser Permanente Division of Research. “This study suggests that we should pay much closer attention to hypoglycemia, even in poorly controlled patients. Providers should explain the symptoms of hypoglycemia, how to treat it, and how to avoid it — for example, by not skipping meals. Most of all, providers should ask all their diabetic patients whether they’ve experienced hypoglycemia, even those patients with very high average levels of blood sugar.”
The researchers surveyed patients with type 2 diabetes being treated with medications to lower their blood sugar and asked about their experiences with severe hypoglycemia. Nearly 11 percent of the more than 9,000 respondents experienced severe hypoglycemia in the prior year, and it occurred at all levels of blood-sugar control.
Researchers categorized patients into five categories of HbA1c, a measure of average blood sugar, ranging from lowest to highest. The prevalence of severe hypoglycemia was calculated for each category. Patients with the lowest and highest HbA1c values tended to be at higher risk for hypoglycemia, compared to those with HbA1c values in the middle range. However, the differences were small and hypoglycemia was common in all HbA1c categories.
“Hypoglycemia is the most common acute complication of diabetes therapy and is associated with poor health outcomes,” said lead author Kasia Lipska, MD, MHS, an endocrinologist from the Yale University School of Medicine. “In clinical trials, patients treated intensively, aiming for excellent blood-sugar control, experienced much more hypoglycemia than patients treated less aggressively. But we didn’t know as much about the relationship between blood-sugar control and hypoglycemia in everyday clinical practice. We wanted to understand whether patients who achieve the lowest average blood sugars are really at the greatest risk for hypoglycemia.”
“It is important to note that it’s not the HbA1c that directly causes hypoglycemia, it’s the therapies we use to lower it,” said Dr. Lipska. “Future research needs to better identify those patients at the highest risk for hypoglycemia so we can reduce the risk. For now, we know that poor control is certainly not protective.”
The researchers suggest that evaluations of quality of diabetes care should include adverse effects associated with treatment, such as hypoglycemia. “While aggressive treatment of high blood sugar was once considered a hallmark of better care, recent clinical trials have raised concerns about the risks of tight control, particularly in the frail and elderly,” said Karter.
Additional authors on the study include Margaret Warton, MPH, and Howard H. Moffet, MPH, of the Kaiser Permanente Division of Research; Elbert S. Huang, MD, MPH, of the University of Chicago School of Medicine; and Silvio E. Inzucchi, MD, and Harlan M. Krumholz, MD, SM, of the Yale University School of Medicine.
About Yale School of Medicine
Founded in 1810, the Yale School of Medicine is a world-renowned center for biomedical research, education and advanced health care. Among its divisions are one of the nation’s oldest schools of public health and the internationally recognized Child Study Center, founded in 1911. Its Yale Cancer Center is one of 41 comprehensive cancer centers designated by the National Cancer Institute. Its 33 academic departments include 11 in the basic sciences, 19 in clinical fields, and 5 in public health. The School of Medicine consistently ranks among the handful of leading recipients of research funding from the National Institutes of Health and other organizations supporting the biomedical sciences, and belongs to medical organizations includinvg the Association of American Medical Colleges (AAMC) and the Association of Academic Health Centers (AAHC). For more information, visit medicine.yale.edu.
About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and the society at large. It seeks to understand the determinants of illness and well-being and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 600-plus staff is working on more than 250 epidemiological and health services research projects. For more information, visit www.dor.kaiser.org.
About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Founded in 1945, our mission is to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve more than 9 million members in nine states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health.