Situation: A 62-year-old woman with chronic kidney disease (CKD) stage G5 performs continuous ambulatory peritoneal dialysis (CAPD) at home with four exchanges a day. Her husband helps her with the exchanges. She attends the hospital's peritoneal dialysis clinic for follow-up. She has type 2 diabetes treated with insulin, and her regimen now includes an overnight icodextrin dwell. What should the nurse remember about her home glucose meter readings?

Icodextrin can falsely raise glucose readings on some meters (those whose strips use glucose dehydrogenase pyrroloquinoline quinone, GDH-PQQ). A falsely high value can hide true hypoglycemia or lead to insulin given in error, which can be fatal, so a glucose-specific method is used for clients receiving icodextrin.

Core mechanism of icodextrin interference
Icodextrin is a glucose polymer added to peritoneal dialysis fluid to sustain ultrafiltration during long dwells, especially the overnight exchange. Once absorbed, it is metabolized to maltose, maltotriose, and maltotetraose. These oligosaccharides are structurally similar enough to glucose that certain point-of-care glucose strips cannot tell them apart ^[1][2]. The problematic chemistry is glucose dehydrogenase pyrroloquinoline quinone (GDH-PQQ). In GDH-PQQ systems, the enzyme oxidizes not only glucose but also maltose and related icodextrin metabolites, producing an electron transfer that the meter reads as glucose. The result is a falsely elevated glucose reading ^[1][2]. This is not a small error; the overestimation can be large enough to push a euglycemic or even hypoglycemic patient into a hyperglycemic range on the meter display.

A falsely high glucose value is clinically dangerous because it can trigger unnecessary insulin administration, which may precipitate severe hypoglycemia—a potentially fatal event. The opposite direction of error, a falsely low reading, is not the characteristic problem with icodextrin and GDH-PQQ strips ^[1][2]. The concern is overestimation, not underestimation.

Watch out! The interference is a property of the test strip chemistry, not the sample site. A fingertip capillary sample does not eliminate the error if the strip still uses GDH-PQQ ^[1][2]. Similarly, draining the peritoneal cavity does not immediately clear maltose and its metabolites from the bloodstream; the interference persists for hours to days after the icodextrin dwell because the metabolites circulate systemically ^[1]. Therefore, options stating that readings become reliable after drainage or that fingertip sampling solves the problem are incorrect.

Which meters are safe
Glucose meters using glucose oxidase (GO) or glucose dehydrogenase with nicotinamide adenine dinucleotide (GDH-NAD) are not affected by icodextrin metabolites ^[1][2]. These methods are more specific for glucose and do not cross-react with maltose, maltotriose, or maltotetraose. The 2011 study by Perera and colleagues specifically tested newer GDH-NAD and GO systems and found that they did not show the overestimation seen with GDH-PQQ ^[1]. The 2016 study by Dogan and colleagues confirmed this distinction in actual CAPD patients using icodextrin versus another hyperosmotic fluid, demonstrating that only the icodextrin-affected strips diverged from serum glucose values ^[2].

Strip enzyme system	Reacts with icodextrin metabolites	Clinical implication
GDH-PQQ	Yes — maltose, maltotriose, maltotetraose	Falsely high glucose; risk of inappropriate insulin
Glucose oxidase (GO)	No	Reliable for patients on icodextrin
GDH-NAD	No	Reliable for patients on icodextrin

Clinical application for the home CAPD patient
This patient has type 2 diabetes on insulin and now uses an overnight icodextrin dwell. Her home glucose meter readings must be interpreted with knowledge of which strip technology she uses. If her meter uses GDH-PQQ strips, the displayed glucose value may be falsely high. A reading of, for example, 180 mg/dL could reflect a true blood glucose of only 90 mg/dL or lower ^[1][2]. Acting on that falsely high number by giving a correction dose of insulin could drive the patient into dangerous hypoglycemia.

The priority nursing action is to verify that the patient is using a glucose-specific meter—one based on glucose oxidase or GDH-NAD—before relying on any home glucose value for insulin dosing. If the meter type is unknown or is GDH-PQQ-based, alternative glucose measurement methods are needed. These may include laboratory serum glucose, a glucose-specific point-of-care device, or, in some settings, continuous glucose monitoring systems that are factory-calibrated and do not use the affected enzyme chemistry . The 2024 review by Galindo and colleagues notes that newer factory-calibrated continuous glucose monitors provide real-time glucose data and may be particularly useful in advanced CKD, where traditional markers such as HbA1c are biased .

Key point! The falsely high reading is not corrected by using a fingertip sample or by draining the peritoneal cavity. The interference is systemic and persists as long as icodextrin metabolites remain in circulation ^[1][2]. The only reliable correction is to use a glucose measurement method that does not cross-react with maltose and related oligosaccharides.