WHEELING, W.Va., May 7 -- Dangerous hypoglycemic episodes are a significant risk for patients with chronic kidney disease, whether they have diabetes or not, researchers said.
The risk of hypoglycemia was increased by 50% among nondiabetic patients with kidney disease compared with similar patients with healthy kidneys, Jeffrey C. Fink, M.D., of the University of Maryland in Baltimore, and colleagues reported online in the Clinical Journal of the American Society of Nephrology.
Action Points
- Explain to interested patients that episodes of low blood sugar are dangerous both immediately and in the long term.
- Explain that this study suggested that chronic kidney disease is a risk factor for hypoglycemia, but point out that the retrospective, records-based study design did not permit conclusions about causality.
- Explain that VA health system patients may not be representative of the general population.
Among diabetic patients, the risk was doubled, they found in a retrospective study of some 243,000 VA health system patients.
The study also found that even episodes of relatively mild hypoglycemia, with blood glucose readings from 60 to 69 mg/dL, increased short-term mortality by 85% or more compared with nonhypoglycemic patients.
"This metabolic disturbance should be considered an important patient safety outcome in chronic kidney disease or diabetes populations," they wrote.
The researchers examined records for VA patients who had at least one acute care hospitalization from October 2004 through September 2005, as well as at least one outpatient measurement of serum creatinine taken from one week to one year before admission.
Patients whose creatinine indicated a glomerular filtration rate of less than 60 ml/min per 1.73 m2 were considered to have chronic kidney disease.
Records were examined for episodes of hypoglycemia during hospitalization or as outpatients, defined as blood glucose less than 70 mg/dL.
Major findings were:
- Diabetic patients: 10.72 episodes per 100 patient-months in patients with chronic kidney disease, 5.33 in patients without (P<0.05)
- Nondiabetic patients: 3.46 episodes per 100 patient-months in patients with chronic kidney disease, 2.23 in patients without (P<0.05)
Adjusted odds ratios for mortality associated with hypoglycemia ranged from 1.85 for inpatients with chronic kidney disease and blood glucose of 60 to 69 mg/dL (95% CI 1.49 to 2.28) to 13.28 for inpatients without kidney disease and blood glucose of less than 50 mg/dL (95% CI 9.20 to 19.18).
Adjustments included age, race, diabetes, Charlson comorbidity index, cancer, and cardiovascular disease.
A somewhat perplexing finding was that mortality following hypoglycemia in patients with kidney disease was no higher than -- and in some comparisons was less than -- the death rate in patients who did not have kidney impairment.
The researchers speculated that patients with kidney disease may receive closer attention and monitoring and hence stave off death longer.
Dr. Fink and colleagues found that chronic kidney disease and diabetes were independent risk factors for hypoglycemia, with diabetes having the stronger apparent effect.
For example, compared with patients who had neither condition the incidence rate ratios for experiencing a moderately severe episode (blood glucose 50 to 59 mg/dL) was 1.58 for those with kidney disease alone and 3.56 for diabetes alone.
But the two conditions appeared to be synergistic when present together. The incidence rate ratio for moderately severe hypoglycemia among patients with both disorders was 7.21.
The researchers said the cause of hypoglycemia in non-diabetic patients with kidney disease "is not entirely clear."
However, they said, the increased rate of hypoglycemia in these patients may account for at least some of the increased cardiovascular morbidity and mortality seen in connection with chronic kidney disease.
"Studies demonstrate that hypoglycemia is associated with cardiac disturbances and an increased incidence of death," they noted.
Dr. Fink and colleagues noted several limitations of the analysis, including its retrospective design and reliance on administrative records; its sample of VA patients, who may not be representative of the general population; and a lack of medication records that may have shed light on the causes of hypoglycemia.
| The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the American Society of Nephrology.
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Primary Source
Clinical Journal of the American Society of Nephrology
Moen M, et al "Frequency of hypoglycemia and its significance in chronic kidney disease" Clin J Am Soc Nephrol 2009; DOI: 10.2215/CJN.00800209.