Blood Sugar Targets in Surgical Intensive Care—Management and Special Considerations in Patients With Diabetes

Abstract

Background: 30-80% of patients being treated in intensive care units in the perioperative period develop hyperglycemia. This stress hyperglycemia is induced and maintained by inflammatory-endocrine and iatrogenic stimuli and generally requires treatment. There is uncertainty regarding the optimal blood glucose targets for patients with diabetes mellitus.

Methods: This review is based on pertinent publications retrieved by a selective search in PubMed and Google Scholar.

Results: Patients in intensive care with pre-existing diabetes do not benefit from blood sugar reduction to the same extent as metabolically healthy individuals, but they, too, are exposed to a clinically relevant risk of hypoglycemia. A therapeutic range from 4.4 to 6.1 mmol/L (79-110 mg/dL) cannot be justified for patients with diabetes mellitus. The primary therapeutic strategy in the perioperative setting should be to strictly avoid hypoglycemia. Neurotoxic effects and the promotion of wound-healing disturbances are among the adverse consequences of hyperglycemia. Meta-analyses have shown that an upper blood sugar limit of 10 mmol/L (180 mg/dL) is associated with better outcomes for diabetic patients than an upper limit of less than this value. The target range of 7.8-10 mmol/L (140-180 mg/dL) proposed by specialty societies for hospitalized patients with diabetes seems to be the best compromise at present for optimizing clinical outcomes while avoiding hypoglycemia. The method of choice for achieving this goal in intensive care medicine is the continuous intravenous administration of insulin, requirng standardized, high-quality monitoring conditions.

Conclusion: Optimal blood sugar control for diabetic patients in intensive care meets the dual objectives of avoiding hypoglycemia while keeping the blood glucose concentration under 10 mmol/L (180 mg/dL). Nutrition therapy in accordance with the relevant guidelines is an indispensable pre - requisite.

Figure 1

Association between mortality and blood glucose levels for critically ill patients. With no pre-existing diabetes mellitus, the curve shows lowest mortality in the range of normal blood glucose levels. This point is displaced towards higher blood sugar levels in diabetic patients. Exactly in which range is the subject of controversial debate. Figure modified from Gunst et al. 2019 (e36).

Figure 2

Concept of stress-induced hyperglycemia with pre-existing diabetes. Insulin resistance and deficiency cause reduced glucose uptake at insulin-dependent organs, increased proteolysis and dyslipidemia (peripheral insulin resistance). Excessive glucose uptake in the liver results in lipogenesis stimulation with the risk of developing non-alcoholic fatty liver disease (NAFLD). In addition, gluconeogenesis is disinhibited (central insulin resistance). Perioperatively, inflammatory stress and iatrogenic interventions increase insulin resistance and subsequently hyperglycemia (stress-induced hyperglycemia), which in turn can potentially influence clinical endpoints. Depiction modified from (28, e37). SIRS, systemic inflammatory response syndrome