Hypoglycemia in the ICU: Discrepancy between capillary and serum glucose measurements in patients with renal disease

Abstract

Recently, a focus on tight glycemic control in intensive care units (ICU) has resulted in implementation of strict insulin protocols requiring frequent glucose monitoring. The use of pointof-care (POC) capillary glucose testing is widespread, but its validity in the ICU has been questioned. Our objective is to better understand the use of POC glucose at the extremes of glycemic control through a case review at our institution. We describe the case of a 75-year-old non-diabetic female with end stage renal disease (ESRD) on hemodialysis who was admitted with apparent hypoglycemia. After extensive workup was done for a seemingly refractive hypoglycemia, a discrepancy between POC capillary glucose and central serum glucose levels was discovered, revealing actual euglycemia and false low POC glucose values. Cases of hypoglycemia can be challenging, especially in non-diabetic patients with ESRD. While glucometers assessing capillary glucose are used both in the outpatient and inpatient environment, their validity in the critically ill patient has known limitations. Cases such as this have led to the development of systemic checks and balances, as well as further investigations regarding the use of POC glucose meters in the ICU. This case serves as a reminder to evaluate for all causes for abnormal laboratory values, including technological limitations.