Will the risk of type 2 diabetes persist for a prolonged period of time after infection with the corona virus? Prof. Dr. Wolfgang Rathmann and his team from the German Diabetes Centre in Düsseldorf searched for answers to this question by analysing the "Disease Analyzer" database. This representative sample includes 35,865 patients up to January 2021 who were diagnosed with COVID-19 and treated by general practitioners. The same number of patients who presented to a GP's office with other acute upper respiratory tract infections (AURI) served as a comparison group.
Using propensity score matching, the researchers made sure that the results were not influenced by factors such as gender, age, health insurance coverage, index month and comorbidity (obesity, hypertension, hyperlipidaemia, cardiac infarction, stroke). The mean age of the cohorts was 42.6 years, 45.6% were women.
In the first 365 days, 189 previously infected COVID-19 patients developed type 2 diabetes, compared with only 175 in the control group, corresponding to an incidence of 15.8 versus 12.3 new cases per 1,000 individuals per year. Consequently, the relative incidence rate was 1.28, which was significant at a 95% confidence interval of 1.05 to 1.57. This means that the risk of developing type 2 diabetes was 28% higher after mild COVID-19 attended by a GP than after any other upper respiratory infection.
Taking into account only those patients who were diagnosed with type 2 diabetes and prescribed blood glucose-lowering medication, the risk remained 26% higher. Taking into account only those people in the control group with a documented negative test for Covid-19 seven days before and after the index visit to their GP, the authors found a 51% higher risk. The incidence rate in this study was only increased for type 2 diabetes, but not for other forms of diabetes or non-specific glucose metabolism disorders.
The authors cite missing data on hospitalisations as one limitation, since only the treating physicians can make entries in the register. In addition, cases of undetected type 2 diabetes or SARS-CoV-2 infections diagnosed outside the GP's office may not have been counted. Besides, even after this study, some questions remain unanswered. For instance, it remains unclear if pre-existing type 2 diabetes may have manifested more quickly due to the immunological activation associated with COVID-19 or due to stress-induced hyperglycaemia.
The question of whether post-COVID diabetes may be reversible after complete recovery also remains open. At any rate, the team of authors advises that glucose metabolism should be closely monitored even after mild cases of COVID-19.
Source:
Wolfgang Rathmann et al: Incidence of newly diagnosed diabetes after Covid-19. Diabetologia (2022).