Study: High glucose levels linked with inpatient death in nondiabetics

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A two-country hospital study of 808 elderly patients found a strong association between high, undiagnosed blood glucose in nondiabetic patients and increased hospital death rates, according to a study in the March issue of the International Journal of Clinical Practice. Researchers are now calling for routine blood glucose testing of elderly patients when they are admitted to hospital.

The Spanish team, led by Pedro Iglesias, MD, from the department of endocrinology at Hospital Ramon y Cajal in Madrid, Spain, looked at 447 consecutive patients admitted to a geriatric unit, while the Italian team, led by Fabio Monzani, MD, from the Department of Internal Medicine at the University of Pisa, Italy, studied 361 patients admitted to an internal medicine department. All patients were older the age of 60 and admited with an acute illness.

They found that when they excluded the 206 patients already diagnosed with diabetes, 25 percent of the remaining 602 patients had a fasting glucose level of 126 mg/dl or more, which is the threshold used to diagnose diabetes, with just under one-fifth of those exceeding 180 mg/dl.

Mortality rates in patients with a fasting glucose level of less than 126 mg/dl was just over 8 percent for both the total sample and the patients admitted without a diagnosis of diabetes. But when the researchers looked at the undiagnosed patients whose fasting glucose levels were 126 mg/dl to 180mg/dl, the death rate rose to 18 percent and, in patients whose levels exceeded 180mg/dl, the rate increased to 31 percent.

These levels were much higher than the 14 and 23 percent recorded for diabetic patients with fasting glucose levels exceeding 126 mg/dl and 180 mg/dl, respectively, the authors wrote.

"This is the first multicenter prospective study to assess the relationship between fasting serum glucose levels and in-hospital mortality in a large cohort of elderly patients," said Iglesias. "Our findings clearly show that fasting glucose is a significant risk factor for death during hospitalization, especially in patients who have not been diagnosed with diabetes."

Other key findings of the study included:

  • The average age of the total cohort was 84 years and 57 percent were female, but the Spanish geriatric cohort was older than the Italian internal medicine cohort (86 versus 80 years), with a higher percentage of women (62 vs. 50 percent).
  • There was a higher incidence of high blood pressure, lower systolic and diastolic blood pressure, higher serum glucose and creatinine and lower total cholesterol concentrations in the Spanish cohort.
  • The five most common reasons for hospital admission in the total cohort were: congestive heart failure (19 percent), respiratory tract infection (12.5 percent), acute cerebrovascular disease (12 percent), exacerbation of chronic obstructive pulmonary disease (9 percent) and cancer (8 percent).
  • 25 percent of the total cohort had a pre-existing diagnosis of diabetes, with 2 percent more patients in the Spanish cohort than the Italian cohort having the disease.
  • Median fasting glucose rates for the total cohort were more than 20 percent higher in patients who died (127 mg/dl) than those who survived (105 mg/dl).
  • Hospital stays averaged 10.5 days for the total cohort and the average time from admission to death was 11.3 days. The Italian internal medicine cohort had a lower death rate (8 vs. 14 percent) and lower average hospital stay (nine days vs. 12 days) than the Spanish geriatric group, but the intervals from admission to death were similar in both groups.

"Our study underlines the importance of testing elderly patients for fasting glucose levels on admission to hospital for acute illnesses and suggests that a blood glucose level of 180 mg/dl or less might be an appropriate target in people who have not been diagnosed with diabetes, said Monzani.

"These findings should help us to identify those patients at high risk during hospitalization, so that they can be offered intensive therapy to reduce their risk of death and improve their prognosis," he said.