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The following is a summary of “Impact of an oral glucose load on IFN-γ-release in persons infected with Mycobacterium tuberculosis,” published in the September 2024 issue of Infectious Disease by Lorentsson et al. 

Hyperglycemia and blood glucose fluctuations may affect interferon-γ (IFN-γ) release in IFN-γ-release assays (IGRAs) used for diagnosing tuberculosis infection (TBI) incubated with M.tuberculosis (Mtb)-specific peptides.    

Researchers conducted a retrospective study to analyze the effects of glucose intake on IFN-γ release and IGRA results during oral glucose tolerance tests (OGTT).   

They examined patients with TB disease (TB) or TBI undergoing a standard 75-g OGTT at the start and end of treatment. Blood for the IGRA QuantiFERON-TB Gold Plus (QFT) containing Mtb-specific tubes (TB1 and TB2), an empty control tube (NIL) and a non-specific mitogen tube (MIT) was drawn at sample-timepoints -15 (baseline), 60, 90, 120 and 240 min during the OGTT. There was a measurement of blood glucose in parallel at all time points while IFN-γ-release (after subtracting NIL) at each time point was compared with baseline using linear-mixed-model analysis.   

The results showed that from 14 participants, 24 OGTTs, IFN-γ-release was increased at sample-timepoint 240 min for TB1; geometric mean (95% confidence interval) 3.0 (1.5–6.2) vs 2.5 (1.4–4.4) IU/mL (P= 0.047), and MIT; 182.6 (103.3–322.9) vs 146.0 (84.0–254.1) IU/mL (P= 0.002). Plasma glucose levels were not linked with IFN-γ-release, and the QFT test results were unaffected by the OGTT.   

They concluded that while glucose ingestion increased IFN-γ-release in the MIT tube, it did not affect plasma glucose levels, QFT test results, or overall IFN-γ-release in IGRAs. 

Source: bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-024-09920-x