3.5.0.0 Glu­cose Meter Ac­cu­ra­cy

Rec­om­men­da­tion

Recommendation

7.9 Health care pro­viders should be aware of the med­i­ca­tions and other fac­tors that can in­ter­fere with glu­cose meter ac­cu­ra­cy and choose ap­pro­pri­ate de­vices for their pa­tients based on these fac­tors. E

Glu­cose me­ters meet­ing U.S. Food and Drug Ad­min­is­tra­tion (FDA) guid­ance for meter ac­cu­ra­cy pro­vide the most re­li­able data for di­a­betes man­agement. There are sev­er­al cur­rent stan­dards for ac­cu­ra­cy of blood glu­cose mon­i­tors, but the two most used are those of the In­ter­na­tion­al Or­ga­ni­za­tion for Stan­dard­iza­tion (ISO 15197:2013) and the FDA. The cur­rent ISO and FDA stan­dards are com­pared in Table 7.1. In Eu­rope, cur­rently mar­ket­ed mon­i­tors must meet cur­rent ISO stan­dards. In the U.S., cur­rently mar­ket­ed mon­i­tors must meet the stan­dard under which they were ap­proved, which may not be the cur­rent stan­dard. More­over, the mon­i­tor­ing of cur­rent ac­cu­ra­cy is left to the man­u­fac­tur­er and not rou­tinely checked by an inde­pen­dent source.

Pa­tients as­sume their glu­cose mon­i­tor is ac­cu­rate be­cause it is FDA cleared, but often that is not the case. There is sub­stan­tial vari­a­tion in the ac­cu­ra­cy of wide­ly used blood glu­cose mon­i­tor­ing sys­tems. The Di­a­betes Tech­nol­o­gy So­ci­ety Blood Glu­cose Mon­i­toring Sys­tem Surveil­lance Pro­gram pro­vides in­for­ma­tion on the per­for­mance of de­vices used for SMBG (https://www.di­a­betestech­nol­o­gy.org/‍surveillance.shtml). In a re­cent anal­y­sis, the pro­gram found that only 6 of the top 18 glu­cose me­ters met the ac­cu­ra­cy stan­dard (57).

Fac­tors Lim­it­ing Ac­cu­ra­cy

Coun­ter­feit Strips. Pa­tients should be ad­vised against pur­chas­ing or re­selling pre­owned or sec­ond-‍hand test strips, as these may give in­cor­rect re­sults. Only un­opened vials of glu­cose test strips should be used to en­sure SMBG ac­cu­ra­cy.

Oxygen. Cur­rently avail­able glu­cose mon­i­tors uti­lize an en­zy­mat­ic reac­tion linked to an elec­tro­chem­i­cal reac­tion, ei­ther glu­cose ox­i­dase or glu­cose de­hy­dro­ge­nase (58). Glu­cose ox­i­dase mon­i­tors are sen­si­tive to the oxy­gen avail­able and should only be used with cap­il­lary blood in pa­tients with nor­mal oxy­gen sat­u­ra­tion. High­er oxy­gen ten­sions (i.e., ar­te­ri­al blood or oxy­gen ther­a­py) may re­sult in false low-‍glu­cose read­ings, and low oxy­gen ten­sions (i.e., high al­ti­tude, hy­pox­ia, or ve­nous blood read­ings) may lead to false high-‍glu­cose read­ings. Glu­cose de­hy­dro­ge­nase mon­i­tors are not sen­si­tive to oxy­gen.

Tem­per­ature. Be­cause the reac­tion is sen­si­tive to tem­per­a­ture, all mon­i­tors have an ac­cept­able tem­per­a­ture range (58). Most will show an error if the tem­per­a­ture is unac­cept­able, but a few will pro­vide a read­ing and a mes­sage in­di­cat­ing that the value may be in­cor­rect.

In­ter­fe­ring Sub­stances. There are a few phys­i­o­log­ic and phar­ma­co­log­ic fac­tors that in­ter­fere with glu­cose read­ings. Most in­ter­fere only with glu­cose ox­i­dase sys­tems (58). They are list­ed in Table 7.2.

Table 7.1—Com­par­i­son of ISO 15197 and FDA blood glu­cose meter ac­cu­ra­cy stan­dards

BG, blood glucose. To convert mg/dL to mmol/L, see http://www.endmemo.com/medical/unitconvert/Glucose.php.
†The range ofBGvalues for which the meter has been proven accurate and will provide readings (other than low, high, or error).
‡Values outside of the “clinically acceptable” A and B regions are considered “outlier” readings and may be dangerous to use for therapeutic decisions128.

Table 7.2—In­ter­fe­ring sub­stances