Lymphocyte Count Correlated to Comorbid Diabetes and COVID-19

At present, it has caused tens of thousands of deaths, and the efficacy of certain antiviral drugs is still under review.

Patients with diabetes are more prone to disease progression than those without diabetes; however the mechanism is not yet clear. Depending on the region, 20% to 50% of patients affected by the COVID-19 pandemic had diabetes. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a reduction in the lymphocyte count of COVID-19 patients.

Medical scientists at the Nanjing Medical University (Wuxi, China) included in a study 63 adult patients with COVID-19 who were admitted to the hospital from January 29 to March 15, 2020. Patients were classified as having diabetes (n=16) or not having diabetes (n=47). Lymphocytes measured and recorded at admission and during treatment were analyzed and compared between groups. Other outcomes assessed in this study included the number of hospitalization days, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid positive days, and minimal lymphocyte count.

Data pertaining to gender, age, type 2 diabetes mellitus (T2DM) status, body mass index (BMI), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were obtained at the time of admission. Data on alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (Cr), and fasting glucose were obtained the next morning after admission. White blood cell count (WBC), C-reactive protein (CRP) and Lymphocytes were measured at admission and during treatment.

The scientists reported that at time of admission, patients with diabetes had a significantly higher maximal C-reactive protein (91.75 mg/L versus 17.0 mg/L) and fasting glucose (8.81 ± 2.42 mmol/L [158.74 ± 43.6 mg/dL] versus 6.01 ± 1.89 mmol/L [108.3 ± 34.1 mg/dL]). A lower minimal lymphocyte count was observed in patients with diabetes versus without diabetes (0.67 ± 0.36 ×10⁹/L versus 1.30 ± 0.54×10⁹/L, respectively). Additionally, the investigators found that the minimal lymphocyte count occurred significantly earlier in patients with diabetes compared with the non-diabetes group (2.68 ± 2.33 days versus 5.29 ± 4.95 days, respectively). Patients with diabetes and COVID-19 also had longer hospital stays (20.44 ± 5.24 days versus 17.11 ± 4.78 days). A negative correlation was found between the minimal lymphocyte count and both hospital days and SARS-CoV-2 nucleic acid positive days.

The authors concluded that COVID-19 patients with T2DM experience a faster decline in lymphocyte count, have lower lymphocyte count, and longer hospital stay than non-diabetic patients. The lower the lymphocyte count, the longer the hospitalization time and viral nucleic acid positive days. The study was published on August 1, 2020 in the journal Diabetes Research and Clinical Practice.


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Nanjing Medical University