Abstract and Introduction
Objective Appropriate glycemic control is fundamental to diabetes care, but aggressive glucose targets and intensive therapy may unintentionally increase episodes of hypoglycemia. We quantified the burden of severe hypoglycemia requiring medical intervention in a well-defined population of insured individuals with diabetes receiving care in integrated health care delivery systems across the U.S.
Research Design and Methods This observational cohort study included 917,440 adults with diabetes receiving care during 2005 to 2011 at participating SUrveillance, PREvention, and ManagEment of Diabetes Mellitus (SUPREME-DM) network sites. Severe hypoglycemia rates were based on any occurrence of hypoglycemia-related ICD-9 codes from emergency department or inpatient medical encounters and reported overall and by age, sex, comorbidity status, antecedent A1C level, and medication use.
Results Annual rates of severe hypoglycemia ranged from 1.4 to 1.6 events per 100 person-years. Rates of severe hypoglycemia were higher among those with older age, chronic kidney disease, congestive heart failure, cardiovascular disease, depression, and higher A1C levels, and in users of insulin, insulin secretagogues, or β-blockers (P < 0.001 for all). Changes in severe hypoglycemia occurrence over time were not clinically significant in the cohort as a whole but were observed in subgroups of individuals with chronic kidney disease, congestive heart failure, and cardiovascular disease.
Conclusions Risk of severe hypoglycemia in clinical settings is considerably higher in identifiable patient subgroups than in randomized controlled trials. Strategies that reduce the risk of hypoglycemia in high-risk patients are needed.
Appropriate glycemic control is a cornerstone of diabetes care. The value of good glycemic control in reducing microvascular complications of diabetes was demonstrated for type 1 diabetes in 1993 by the Diabetes Control and Complications Trial and for type 2 diabetes in 1998 by the United Kingdom Prospective Diabetes Study (UKPDS).[3–5] In response to these findings, early national standards of diabetes care defined the acceptable level of glycated hemoglobin (A1C) as <8% for most patients with diabetes. In 2002, the American Diabetes Association decreased the target A1C for adults to <7%. Changes in national guidelines and the addition of new glucose-lowering medications resulted in a dramatic decrease in A1C levels in the U.S. from a mean A1C of 8.2% in 1996 to 7.2% in 2006. In 2008, results of the Action to Control Cardiovascular Risk in Diabetes (ACCORD), Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE), and Veterans Affairs Diabetes Trial (VADT) trials, follow-up from the Steno-2 and UKPDS trials, and multiple epidemiological studies of A1C level and treatment intensification[15,16] began to raise concerns about the risks of aggressive treatment and suggested that A1C goals should be individually customized[10,17] based on anticipated benefits and risk of therapy, including increased risk of severe hypoglycemia with more aggressive glucose and A1C goals.[18–20]
Hypoglycemia can be a life-threatening complication of diabetes as well as a major source of anxiety and a threat to quality of life.[21,22] A recent study of 33 million Medicare patients demonstrated that although hospital admission for hyperglycemia events declined ~39% from 1999 to 2011, the admission rates for hypoglycemia increased ~12%, and hypoglycemia is now the most common acute metabolic event leading to hospitalization. Most estimates of severe hypoglycemia risk are derived from clinical trials, in which event rates range from 0.3 to 1 per 100 person-years of observation.[11,18,24] However, the Medicare data described above and other observational studies suggest that severe hypoglycemia in community-treated patients is much more common than indicated by clinical trial data.[25–27] Additional evidence from clinical trials suggests that the increased risk of hypoglycemia in the absence of the strict oversight present in clinical trials may also be related to a variety of other factors, including age, cardiovascular and kidney function, cognition, body weight, diabetes duration, and glucose-lowering agent use.[28,29]
Having established the SUrveillance, PREvention, and ManagEment of Diabetes Mellitus (SUPREME-DM) DataLink, which represents the largest insured diabetes patient cohort with data from electronic health records in the U.S. outside of the Veterans Administration, we sought to quantify the burden of severe hypoglycemia requiring medical intervention in a well-defined community population. Specific goals of the current study were to quantify the occurrence of severe hypoglycemia among insured, community-treated adults with diabetes; to identify subgroups of individuals at high risk of severe hypoglycemia; and to report trends in hypoglycemia over time as a whole and among different subgroups. On the basis of experiences in clinical practice and the clinical trial findings described above, we hypothesized that rates of severe hypoglycemia would be higher among patients treated with insulin who are elderly and have multiple comorbid conditions.
Diabetes Care. 2016;39(3):363-370. © 2016 American Diabetes Association, Inc.