You are presented with a paragraph from a COVID-19 literature. Classify the topics of this piece of text by choosing from the following categories:

- Epidemic Forecasting: The content relates to predictions about the spread of COVID-19.
- Treatment: The paragraph discusses therapeutic methods or medication for COVID-19.
- Prevention: The content covers measures to prevent the spread of COVID-19.
- Mechanism: The paragraph explains the biological mechanisms of the virus.
- Case Report: The content is a report of a COVID-19 case.
- Transmission: The paragraph discusses how COVID-19 is transmitted.
- Diagnosis: The content is about diagnosing COVID-19 in individuals.

Your classification should be provided as an element within a JSON array. The array should be formatted with topics enclosed in double quotes and separated by commas, following the JSON format, for example: ["Topic1", "Topic2", ...]. Include all applicable topics within the array. Your output should be a valid JSON array, and no additional text should be included in your response.

Article:

BACKGROUND: Diabetes is a known risk factor for severe coronavirus disease 2019 (COVID-19). We conducted this study to determine if there is a correlation between hemoglobin A1c (HbA1c) level and poor outcomes in hospitalized patients with diabetes and COVID-19. METHODS: This is a retrospective, single-center, observational study of patients with diabetes (as defined by an HbA1c >/= 6.5% or known medical history of diabetes) who had a confirmed case of COVID-19 and required hospitalization. All patients were admitted to our institution between March 3, 2020 and May 5, 2020. HbA1c results for each patient were divided into quartiles; 5.1-6.7% (32-50 mmol/mol), 6.8-7.5% (51-58 mmol/mol), 7.6-8.9% (60-74 mmol/mol), and >9% (>75 mmol/mol). The primary outcome was in-hospital mortality. Secondary outcomes included admission to an intensive care unit, invasive mechanical ventilation, acute kidney injury, acute thrombosis, and length of hospital stay. RESULTS: Five hundred and six patients were included. The number of deaths within quartiles 1 through 4 were 30 (25%), 37 (27%), 34 (27%) and 24 (19%), respectively. There was no statistical difference in the primary or secondary outcomes between the quartiles except acute kidney injury was less frequent in quartile 4. CONCLUSIONS: There is no significant association between HbA1c level and adverse clinical outcomes in patients with diabetes who are hospitalized with COVID-19. HbA1c should not be used for risk stratification in these patients.
["Diagnosis", "Treatment"]