it is important to recognize other physiologic markers such as lactate elevation and to include adjustment for severity of illness such as the Apache II score in comparative analyses. It is conceivable, although not specifically suggested by the evidence, that some form of “early worsening” could result from overly aggressive correction. Randomized trials would be needed to attempt to discern optimal levels of glycemia in relation to preadmission glycemic control of diabetes, according to comorbidities.
We believe that advances in technology for monitoring and treatment may improve our ability to achieve and maintain specific targets, permitting effective randomization in clinical trials that are designed to test hypotheses related to condition-specific assignment of glycemic targets.1,73 After further study, if the impression that hyperglycemia should be approached cautiously according to preadmission HbA1c elevations is upheld, then one approach would be that hospitalized patients with uncontrolled diabetes should have higher glycemic targets for the short term than other patients hospitalized with the same conditions. An alternative approach would be that the universal targets, if applicable, should be approached more slowly for patients with uncontrolled diabetes. On the other hand, a strong case can be made that before elective surgery, glycemic control should be optimized safely, in the ambulatory setting.
Table 3.4
| Patient group | Therapeutic blood glucose target, mg/dL |
| Without diabetes | 140–200 |
| With diabetes, HbA1c <7% | 140–200 |
| With diabetes, HbA1c ≥7% | 160–220 |
| Cardiac surgery, without diabetes | 140–180 |
| Cardiac surgery, with diabetes, HbA1c <7% | 140–180 |
| Cardiac surgery, with diabetes, HbA1c ≥7% | 160–200 |
Conclusion
Observational data suggest that glycemic variability may be an independent predictor of adverse hospital outcomes. To confirm a causal relationship between variability and outcomes, interventional trials are required that have the capability of randomizing patients to greater or lesser variability while maintaining similar mean glycemia. Methods for future research and treatment might include improvements in glycemic monitoring and insulin delivery algorithms, as well as non-insulin-based therapeutic interventions, including incretin-based therapies. It is hoped that improvement in therapeutic regulation of glycemic control will be capable of reducing glycemic variability. Importantly, at the present time, providers may have relatively little control over glycemic variability.
In contrast, the actions of providers may determine whether or not patients experience acute correction of chronic hyperglycemia. In the presence of diabetes, chronic hyperglycemia may increase the risk for adverse outcomes, especially for patients considering elective surgery. For some outcomes among critically ill populations, however, the impact of chronic hyperglycemia in the presence of diabetes may be less than the impact of stress hyperglycemia of comparable magnitude among patients without diabetes. Any mechanisms of harms from rapid correction are unknown at this time, but they would not necessarily be limited to harms of the concomitant risk of hypoglycemia. Harms from rapid correction of chronic hyperglycemia are not yet proven to outweigh potential benefits. The balance between harms (if any) and benefits of rapid correction of chronic hyperglycemia are likely to differ according to comorbidities, concomitant therapies, site of care, and the underlying reasons for admission.
We conclude that it is premature to establish specific cautionary guidelines about the correction of chronic hyperglycemia for hospitalized patients with diabetes, but acknowledge evidence suggestive that these guidelines could differ from recommendations for the general population. Analysis will be complex, with due consideration for the importance of glycemic control to concomitant medical conditions, in the presence of diabetes. A take-home message may be that caregivers should “stay tuned” to personalized glycemic targets in the hospital and, for now, should ascertain the HbA1c or indicators of preadmission glycemic control and at least consider the results when individualizing patient care plans.
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