Hypoglycemia and Clinical Outcomes in Hospitalized Patients With Diabetes: Does Association With Adverse Outcomes Remain When Number of Glucose Tests Performed Is Accounted For?

BACKGROUND: Hypoglycemia is associated with increased length of stay in hospital patients, but previous studies have not considered the confounding effect of increased hypoglycemia detection associated with increased capillary blood glucose (CBG) measurement in prolonged admissions. We aimed to determine the effect of recorded hypoglycemia on length of stay of hospital inpatients (LOS) when this mathematical association is subtracted.
METHODS: CBG data were analyzed for inpatients within our health board area (01/2009-01/2015). A simulated CBG data set was generated for each patient with an identical sampling frequency to the measured CBG data set. The mathematical component of increased LOS was determined using the simulated data set. Subtraction of this confounding mathematical association was used to provide measurement of the true clinical association between recorded hypoglycemia (CBG < 4 mmol [< 72mg/dl]) and LOS.
RESULTS: A total of 196 962 admissions of 52 475 individuals with known diabetes were analyzed. 68 809 admissions of 29 551 individuals had >4 CBG measurements made and were included in analysis. After subtraction of the mathematical association of increased sample number, the clinical effect of recorded hypoglycemia is reduced-but persists-compared to previous studies. 1-2 days with recorded hypoglycemia has a relatively minor effect on LOS. LOS increases rapidly if there are ≥3 days with recorded hypoglycemia, with an increase of 0.75 days LOS per additional day with hypoglycemia.
CONCLUSIONS: This technique increases accuracy of economic modeling of the impact of hypoglycemia on health care systems. This could assist study of the impact of hypoglycemia on other outcomes by factoring for bias of increased sample numbers.