Mean platelet volume (MPV): new diagnostic indices for co-morbidity of tuberculosis and diabetes mellitus.

Background: Tuberculosis (TB) and type 2 diabetes mellitus (DM) are global health diseases with high morbidity and mortality. Few studies have focused on platelet indices in TB-DM coinfection patients. The objective of this work was to analyze the platelet indices in TB, DM and TB-DM patients to assess the predictive value of the platelet index for the risk of these diseases.

Methods: In total, 246 patients admitted to our hospital were distributed into three groups (113 TB, 59 DM and 74 TB + DM). A total of 133 individuals were also recruited as healthy controls (HC). Platelet indices, namely, platelet count (PC), mean platelet volume (MPV), plateletcrit (PCT) and platelet distribution width (PDW), were compared among the four groups, and the relationship with inflammatory markers was explored by using statistical software.

Results: Our study discovered that MPV and PCT were significantly downregulated in TB + DM patients (9.95 ± 1.25 fL, 0.20 ± 0.05%, P < 0.0001, P = 0.0121, separately) compared with DM individuals (10.92 ± 1.17 fL, 0.22 ± 0.04%). Moreover, the changes in MPV were significantly higher in TB + DM patients (9.95 ± 1.25 fL, P = 0.0041) than in TB patients (9.42 ± 1.01 fL). No differences were found in PLT and PDW among the four groups (P > 0.05). The sensitivity and specificity of MPV in the differential diagnosis of DM patients vs TB + DM patients were 64.9 and 66.1% (P < 0.0001), respectively, and the sensitivity and specificity of MPV between TB patients and TB + DM patients was 60.8 and 66.4%, respectively (P = 0.003). MPV improved the diagnosis sensitivity when it was combined with clinical parameters, such as fasting blood glucose in DM and Mycobacterium tuberculosis culture result in TB (76.3% vs 64.9, 72.6% vs 60.8%, P < 0.0001, P = 0.001, respectively). In addition, the sensitivity and specificity of PCT in the differential diagnosis of DM patients vs TB + DM patients were 69.5 and 59.4%, respectively (P = 0.008). PCT improved the diagnosis sensitivity when combined with fasting blood glucose in DM (72.9% vs 64.9%, P = 0.004). In addition, MPV was linked to CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate) in the TB + DM patients (r = 0.3203, P = 0.0054, r = 0.2504, P = 0.0307) but PCT was not (r = 0.1905, r = 0.008675, P > 0.05, respectively).

Conclusions: Our research shows that MPV and PCT might be good clinical laboratory markers to distinguish TB + DM patients from TB or DM individuals, thus providing support for earlier clinical diagnosis, prevention, and therapy.