Limited health literacy increases safety risks for patients with diabetes

People with diabetes who have limited health literacy are at higher risk for hypoglycaemia or low blood sugar, according to a new study from researchers at the University of California, San Francisco and the Kaiser Permanente Division of Research in Oakland, CA.

The team surveyed more than 14,000 adults with diabetes who are part of the Diabetes Study of Northern California (DISTANCE), making it the largest observational study to assess significant hypoglycemia in the United States. Results were based on self-reported hypoglycemia that required individuals to get assistance and/or to have treatment for a reaction.

Researchers found that those with limited health literacy are at higher risk of significant hypoglycemia. The team defined limited health literacy as patients reporting difficulties reading health-related materials.

Findings appear in the Journal of General Internal Medicine and are available online on 19 May 2010.

"The frequency of significant hypoglycaemia suggests that more surveillance and monitoring are needed. Physicians need to ask diabetes patients about hypoglycaemia symptoms at every visit. Our results also highlight the need to be careful about performance standards for glucose control in diabetes. There may be unintended consequences, like significant hypoglycaemia, in trying to achieve strict glucose control for all diabetes patients," said Urmimala Sarkar, MD, MPH, lead author of the study. Sarkar is with the UCSF Center for Vulnerable Populations and the UCSF Division of General Internal Medicine at San Francisco General Hospital.

In type 2 diabetes, the most common form of diabetes, either the body does not produce enough insulin or cells ignore the insulin. This leads to chronically elevated blood sugar.

Hypoglycaemia is low blood sugar which, in patients with type 2 diabetes, can be caused by medicines used to treat their disease, if medications are not taken as instructed. If left untreated, hypoglycaemia may lead to unconsciousness. In addition, episodes of low blood sugar can have long-term consequences such as dementia., explain the researchers.

"This study is a wake-up call for clinicians. Serious hypoglycaemic events occur more often than are clinically recognised, especially among patients who may have difficulty understanding written materials. Providers and pharmacists need to ensure that their patients fully understand the instructions that come with each medication or patient safety may be compromised," said Andrew J. Karter, PhD, principal investigator of the DISTANCE Study and senior research scientist at the Kaiser Permanente Division of Research in Oakland, CA.

Investigators determined patients’ levels of health literacy by asking patients to report problems due to reading, understanding, and filling out forms, not due to poor vision. Patients had the option to respond online, in writing or using the telephone. The researchers also asked whether study participants had experienced hypoglycaemia severe enough to require assistance. The researchers found that:

• 11 percent of the respondents experienced hypoglycaemia requiring assistance in the past 12 months, much higher than expected from prior clinical trials;
• 59 percent of those taking insulin had significant hypoglycaemia that required assistance;
• Patients commonly reported limited health literacy: 53 percent reported problems learning about health, 40 percent needed help reading health materials, and 32 percent were not confident filling out medical forms by themselves;
• Respondents with limited health literacy were 30-40 percent more likely to experience hypoglycaemia compared to those with adequate health literacy.

Data collection and analyses for this study was conducted by the NIH-funded DISTANCE study, which enrolled a sample of patients from the Kaiser Permanente Northern California Diabetes Registry. The overarching aim of DISTANCE is to investigate ethnic and educational disparities in diabetes-related behaviours, processes of care and health outcomes.

(Source: Kaiser Permanente Division of Research: Journal of General Internal Medicine: June 2010)