Drug Interference in Self-Monitoring of Blood Glucose and the Impact on Patient Safety: We Can Only Guard Against What We Are Looking for

Self-monitoring of blood glucose is a key aspect of diabetes management. Depending on the technology used, however, various substances can jeopardize the reliability of the measurements and precipitate complications with potentially life-threatening consequences when blood glucose was deemed well-controlled. As such, it is important for all involved to be aware of those factors. Officially suggested procedures for testing and alternatives have each their own advantages and limitations, and interferences may be found beyond the substances to be tested provided by the various pertinent institutions. This article reviews these pros and cons and illustrates how interference testing beyond established standards contributes to patient safety. Once identified, interfering substances are included in product labeling and healthcare professionals and users need to be trained to be aware of these risks.

Real-world data from Europe and Africa suggest that accuracy of systems for self-monitoring of blood glucose is frequently impaired by low hematocrit

AIMS

Certain systems for self-monitoring of blood glucose (SMBG) demonstrate inaccuracy at low and high hematocrit (HCT). Manufacturers define HCT ranges for accurate performance. Our objective was to assess the frequency of HCT values that can lead to clinically relevant errors.

METHODS

In this cross-sectional study, we collected real-world data representing over 360,000 outpatients from the Netherlands (NL), the Czech Republic (CZ), and South Africa (ZA). These were subsequently stratified by sex and age and compared to commonly specified HCT range limits, reference intervals, and data from 1780 healthy Czech subjects.

RESULTS

HCT values were comparably distributed in NL and CZ. Outpatients had a higher dispersion of values than healthy subjects. Low HCT values in Europe were common in age groups with a high prevalence of diabetes. All ZA age groups showed a higher prevalence of low HCT than in Europe.

CONCLUSIONS

Real-world data indicate that SMBG systems specified to perform only within the frequently used 30-55% HCT range would leave 3% of outpatients in Europe and 18% in South Africa at risk of false SMBG results, with individual age strata being substantially higher. This could affect their diabetes management. Adequate SMBG systems should thus be chosen.

The protein truncation test in mutation detection and molecular diagnosis

The protein truncation test (PTT) is a simple and fast method to screen for biologically relevant gene mutations. The method is based on the size analysis of products resulting from in vitro transcription and translation. Proteins of lower mass than the expected full-length protein represent translation products derived from truncating frame shift or stop mutations in the analyzed gene. Because of the low sensitivity of the conventional PTT mutations can be detected only in those samples, which harbor a high relative number of mutated gene copies. This disadvantage can be overcome by technical modifications and advanced forms of the PTT. Modifications like gene capturing and the digital PTT lower the detection limit and thus allow the use of the PTT in the detection of mutations in body fluids. Another disadvantage of the conventional PTT is the use of radioactive labels for protein detection. Recently, modifications like fluorescent labels or the use of tagged epitopes were established, which allow the detection of the nonradioactive translation product. When several epitopes in different reading frames are used, the mutation detection spectrum can be expanded to all possible frame shift mutations. These modifications transform the PTT into a powerful nonradioactive technique to detect mutations with high sensitivity.