In this large observational single institutional sample, treatment intensification occurred in less than 1/4 of days when hyperglycemia occurred. There was a strong association between the frequency of both scheduled and sliding scale insulin intensification and the magnitude of decline in mean daily blood glucose. These findings are consistent with studies in outpatient settings which demonstrate that (1) treatment intensification is infrequent and (2) low frequency of treatment intensification is associated with reduced achievement of glycemic goals.
Although tight glycemic control has been shown to improve outcomes in some critically ill patients, it is unknown whether intensive glycemic control has benefits outside of an ICU environment. No randomized, controlled, interventional trials have been conducted to assess this. Such trials would be logistically difficult for multiple reasons, including the lack of available protocols for antihyperglycemic treatments with strategies besides intravenous insulin. These results, which show a direct relationship between the frequency of insulin intensification and the magnitude of blood glucose reductions, suggest a potential strategy for the reduction of hyperglycemia in a non-ICU general inpatient ward setting, where intravenous insulin typically is not used.
These findings are consistent with prior evaluations supporting the utility of scheduled insulin intensifications.14
Although there is general agreement in the literature that the sliding scale method is not very effective,9,14,21–24
this study found that intensification of sliding scale insulin also was associated with a significant decrease in blood glucose levels.25
No association between intensification of oral diabetic agents and reduction of hyperglycemia was found. Fear of hypoglycemia is a commonly cited concern for frequent insulin intensification among hospitalized patients.26
In this study, the incidence of hypoglycemia was similar with or without intensification.
In the outpatient treatment of diabetes, numerous factors impede the successful treatment of hyperglycemia, including access to care, patient adherence, and availability of home glucose data.16,27,28
Many of these factors are absent in the inpatient setting, and therefore effective process of care, including timely treatment intensification, acquires prominence among determinants of glycemic outcomes. However, there are also potential obstacles to intensification that exist only in the inpatient setting, such as a change in the patient’s clinical status, rapidly decreasing glucocorticoid dose, or anticipation of discharge, that must also be addressed. In our study, similar to previous reports,13
rates of treatment intensification continue to be low.
This evaluation has a number of strengths. Because of the availability of electronic data in our local institution, we were able to evaluate several thousand ethnically and socioeconomically diverse patients. Unlike most of the previously published reports on outcomes of treatment of inpatient hyperglycemia, which focused on patients treated in the intensive care unit, our study analyzed treatment of hyperglycemia in the general ward, where most of the diabetic patients are hospitalized.
It should also be noted that there was a small but significant unadjusted decline in mean daily blood glucose among the patients who never received an intensification of therapy (Fig. ). This could be caused by a transient elevation in blood glucose in the acute setting that later spontaneously improved with the resolution of illness. Inability to account for the changes in the patient’s clinical status is therefore a potential limitation of this study.9
However, in the fully adjusted model, this trend should result in a conservative estimate of the effect that intensification had on the change in the blood glucose.
There are several limitations to this study. Only inpatient glucose and medication data for patients were available. Thus, outpatient glycemic control before admission could not be determined, and comparison between outpatient and inpatient antihyperglycemic medication regiments (both pre- and posthospitalization) could not be performed. In a retrospective observational analysis, the inability to capture and incorporate all of the potential factors affecting the outcome of interest can introduce bias in the analysis. In addition, missing data can create bias in the results. Also, all medication intensifications were measured from the CPOE data because medication administration records were only available on paper. While these are generally accurate in terms of dosing, more variability exists regarding the time of administration. The study attempted to minimize this by evaluating dose changes by days, and allowing both the same day and the next day to count as a successful intensification after a hyperglycemic episode. In addition, while glucocorticoid administration was included in the model for adjustment, hyperglycemia among patients can be dose-dependent, and glucocorticoid dosage was not included in the model. Patients who stayed in the hospital less than 3 days were excluded from the study and therefore the study findings are not applicable to this population. The generalizability of the results is also limited by single institutional evaluation.
In summary, this study demonstrates an association between the frequency of both scheduled and sliding scale insulin intensification and the magnitude of decline in the mean daily blood glucose in diabetic patients hospitalized on the general ward. Further studies are needed to establish whether decrease in blood glucose levels leads to improvements in the clinical outcomes in this patient population.