August 7, 2013
Severe Hypoglycemia Occurs at All Levels of Blood Sugar Control in Patients Medicated for Diabetes

Oakland, CA—Severe hypoglycemia can occur in patients being treated for diabetes, no matter how well their condition is controlled with medications, according to a new study.

Study authors note that their research, published recently in Diabetes Care, challenges conventional wisdom that hypoglycemia is primarily a problem among patients with tightly controlled diabetes whose average blood sugar levels are lower.

“Severe hypoglycemia was common among patients with type 2 diabetes across all levels of glycemic control. Risk tended to be higher in patients with either near-normal glycemia or very poor glycemic control,” according to the researchers.

Background in the article makes a distinction between low blood sugar, which is easily treatable with glucose-rich food or drink, and severe hypoglycemia, which can result in dizziness or mental confusion and requires medical intervention. Left untreated, injury, car accidents, comas or even death can occur, in some cases, according to the authors, who also cited recent studies indicating that patients who experienced severe hypoglycemia were at higher risk for dementia, falls, fractures, and cardiovascular effects.

“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.”

Researchers from the University of Chicago and Yale University, as well as Kaiser Permanente, surveyed patients with type 2 diabetes being treated with medications to lower their blood sugar and asked about their experiences with severe hypoglycemia. Of the more than 9,000 respondents to the survey, conducted from 2005 to 2006, nearly 11% said they had experienced severe hypoglycemia in the prior year.

Survey respondents, who ranged in age from 30 to 77 years of age, were all type 2 diabetes patients in a large, integrated health care system being treated with glucose-lowering therapy. The survey, with a 62% response rate, asked if patients had experienced severe hypoglycemia requiring assistance in the previous year.

Based on the study’s five categories of HbA1c, patients with the lowest and highest values tended to be at higher risk for hypoglycemia, compared to those with HbA1c values in the middle range, according to the report. Researchers cautioned that the differences were small, however, and hypoglycemia was fairly common in all HbA1c categories. “Across HbA1c levels, rates of hypoglycemia were 9.3–13.8%. Compared with those with HbA1c of 7–7.9%, the RR of hypoglycemia was 1.25 (95% CI 0.99–1.57), 1.01 (0.87–1.18), 0.99 (0.82–1.20), and 1.16 (0.97–1.38) among those with HbA1c <6, 6–6.9, 8–8.9, and ≥9%, respectively, in a fully adjusted model,” according to the report. Age, diabetes duration, and type of diabetes medication did not appear to have a significant effect on the relationship between HbA1c and hypoglycemia.

“Hypoglycemia is the most common acute complication of diabetes therapy and is associated with poor health outcomes,” stated lead author Kasia Lipska, MD, MHS, an endocrinologist at 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 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.”

In evaluating the quality of diabetes care, adverse effects associated with treatment, such as hypoglycemia, should be taken into consideration, not just that the HbA1C value meets a specific guideline, the authors suggested.

“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,” Karter pointed out.

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