glucometers , which employ the glucose dehydrogenase pyrroloquinoline quinone ( gdh - pqq ) are known to produce falsely high recordings of capillary glucose in the presence of interfering substances like maltose and galactose .
the food and drug administration ( fda ) did recommend that these meters should not be used in hospital settings . following this
public health notification gdh - pqq glucometers have been supplanted by glucometers using mutant variant of quinoprotein glucose dehydrogenase ( mutq - gdh ) chemistry which is a maltose independent advanced chemistry .
we report a child who had falsely high capillary glucose values with a mutq - gdh glucometer .
the child was later proven to have galactosemia and the falsely high capillary glucose was due to a cross reaction with galactose .
a 2-month - old male child was admitted to our hospital for jaundice and failure to thrive .
admission arterial blood gas was suggestive of compensated metabolic acidosis with a high anion gap .
random capillary glucose was performed , which revealed a value of 310 mg / dl [ table 1 ] .
lab results of the patient on the first day of hospitalization subsequent readings taken every hour for the next 6 h were above 250 mg / dl .
capillary glucose testing was performed using accu - check 
  performa ( roche diagnostics , mannheim , germany ) glucometer . in view of suspected diabetic ketoacidosis ,
an endocrinology consultation was sought and hydration and insulin infusion were considered . however , the corresponding random venous plasma glucose was 67 mg / dl ( performed using glucose oxidase method ) and there was an absence of glucosuria .
hence , it was decided to withhold insulin infusion and potentially fatal hypoglycemia was avoided . in view of a possible cross reaction of high galactose with the glucometer , which employs a mutq - gdh chemistry further testing
a quantitative test for galactose-1-phosphate uridyl transferase in whole blood showed a value of 3.85 u / g hb ( normal range 11 - 41.0 u / g hb ) .
quantitative test for galactose 1-phosphate in red blood cell was 1.8 mg / dl ( normal range 0 - 1 mg / dl ) .
a liver biopsy revealed macrovesicular steatosis with bile duct proliferation and a fibrosis score of 4/6 [ figure 1 ] .
liver biopsy showing macrovesicular steatosis ( white arrow ) and bileduct proliferation ( black arrow ) the child was started on a galactose free formula .
he showed steady improvement with resolution of jaundice and weighed 4.0 kg on repeat examination 1 month later .
galactosemia is a rare condition with a prevalence of 1 in 60,000 live births among caucasians .
diagnosis of galactosemia is usually made by a new born screening test in western countries . in india ,
a prospective screening study for galactosemia in 18,000 newborns in india identified a single case of galactosemia with an estimated prevalence of 1:10,300 .
point of care testing devices like glucometers are increasingly being used in hospital care settings .
hence , it is important that the practicing clinician is aware of the technical deficiencies associated with these devices .
pre - analytical errors include damage to the test strip or incomplete deposition of reagent on the test strip .
analytical errors deal with the technique of testing and includes insufficient or excessive blood loading , miscoding , calibration errors and those arising from contamination .
operator dependent errors can be divided into two , namely those involving glucometers using glucose oxidase chemistry and those involving gdh - pqq chemistry .
hypertriglyceridemia , hyperuricemia , hypoxia and acetaminophen can interfere with glucometers using the glucose oxidase chemistry .
diet or medication containing excessive galactose , maltose , xylose and vitamin c can interfere with glucose dehydrogenase ( gdh ) biosensor . a previous analysis of the food and drug administration 's ( fda ) manufacturer and user facility device experience ( maude ) data base for gdh - pqq glucometer has listed two cases of severe hypoglycemia ( non - fatal ) in children with galactosemia and these events happened despite warnings by both manufacturers and regulatory authorities . to our knowledge , this is the first clinical case report of a falsely high glucose reading due to high galactose in a proven case of galactosemia with a glucometer using the mutq - gdh chemistry ( a modified gdh - pqq chemistry ) .
the package insert of the glucometer cautions that galactose levels greater than 15 mg / dl ( 0.83 mmol / l ) can cause overestimation of glucose values . according to a previous biochemical study galactose levels more than 39 mg / dl ( 2.2
mmol / l ) had significant interference with the glucometer test strips and can produce a falsely high reading . in developing countries where there is no new born screening for galactosemia a sick infant with high galactose levels is at risk for developing iatrogenic hypoglycemia . based on our experience , we suggest precautionary measures to prevent a medical misadventure .
all stakeholders including doctors , nurses , diabetic educators and caregivers of galactosemia patients should be made aware of the pitfalls of mutq - gdh - pqq chemistry based glucometers .
 we report a 2-month - old child with galactosemia and falsely high glucose readings with a glucometer using mutant variant of quinoprotein glucose dehydrogenase ( mutq - gdh ) chemistry . 
 potentially fatal hypoglycemia could have been induced in the child if insulin infusion had been initiated as per glycemic management protocol . 
 even though , the product information with the glucometer carries warning regarding interference by high galactose levels , the awareness regarding this interaction is generally poor in many practice settings . 
 although , false readings have been reported with glucose dehydrogenase pyrroloquinoline quinone ( gdh - pqq ) glucometers , to our knowledge this is the first case report of a falsely high glucose reading due to high galactose in a proven case of galactosemia with a glucometer using the mutq - gdh chemistry ( a modified gdh - pqq chemistry ) . 
 our experience has prompted us to write this case report and we suggest avoiding these glucometers in neonates and infants when a metabolic disease is suspected . 
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