Association of Blood Glucose Control and Outcomes in Patients with COVID-19 and Pre-existing Type 2 Diabetes

Peer Reviewed and published in Cell Metabolism.  Retrospective analysis.

Diabetes has been found to be a risk factor for poor outcomes in COVID-19 infected patients in previous studies.  This study specifically looked at outcomes in patients with well-controlled versus poorly-controlled pre-existing diabetes.  Hyperglycemia versus strict glucose control have yielded conflicting results in pre-COVID-19 studies raising the question of what is the appropriate level of glucose control that will avoid complications of hyperglycemia while also avoiding hypoglycemia and its complications when battling this new infection.

This study was a retrospective longitudinal, multi-centered study from a cohort of 9,663 confirmed COVID-19 cases enrolled among 19 hospitals in Hubei Province, China, focusing on the association between plasma glucose levels and clinic outcomes in COVID-19 patients with T2D. Out of the 9,663 patients over 2,000 were excluded from analysis due to having a secondary medical condition that may be unrelated to infection such as type 1 diabetes and heart failure, were pregnant, extremes of age (<18 or >75) or did not have a complete medical record.  Of the remaining 7,337 patients, 952 of them had pre-existing diabetes.  The pre-existing diabetes group was further separated on glycemic control.

1. Well-controlled BG was defined when glycemic variability ranged from 3.9 to 10.0 mmol/L (70-180 mg/dL).  Total n = 282
2. Poorly-controlled BG was defined when the lowest fasting BG was above or equal 3.9 mmol/L ( 70 mg/dL) and the highest 2 hPG level exceeded 10.0 mmol/L (180 mg/dL). Total n = 528

Propensity Score-Matched Analysis followed by a sensitivity analysis were performed. 

• The in-hospital death rate was significantly higher in patients with pre-existing T2D relative to the non-diabetic individuals (7.8% versus 2.7%, p < 0.001). 
• The in-hospital death rate was significantly lower (1.1% versus 11.0%) in the well-controlled group relative to the poorly controlled group. 
• After adjusting for age, gender, the severity of COVID-19, comorbidities, and site effect, the HR of the all-cause mortality in the well-controlled BG group versus the poorly controlled BG group was 0.13 (95% CI, 0.04–0.44; p < 0.001)

In conclusion, T2D is an important risk factor for COVID-19 progression and adverse endpoints, and well-controlled BG, maintaining glycemic variability within 3.9 to 10.0 mmol/L, is associated with a significant reduction in the composite adverse outcomes and death. These findings provide critical insights into the clinical characteristics of patients with COVID-19 and pre-existing T2D and the possible avenues to improving their disease outcomes.