how to combine 2 json in query

I need to append 2 JSON.
Currently it is printing as two separate Json.
How do I combine both of my reading???? I want Bothe readings in one JSON

Code Block let query = HKSampleQuery(sampleType: glucoseType!, predicate: predicate, limit: 5, sortDescriptors: nil) { (query, results, error) in
   for result in results as! [HKQuantitySample] {
    let bloodGlucose = result.quantity.description
    let bloodGlucoseItem = HealthDataItem(endDate: result.endDate, value: String(bloodGlucose), startDate: result.endDate, type: .bloodGlucose)
   let healthData = [bloodGlucoseItem]
    do {
     let data = try JSONEncoder().encode(healthData)
     let json = String(data: data, encoding: String.Encoding.utf8)
     print("json data:", json as Any )
         resolve(json)
             } catch {
                               //error handling
                          }
                }
            }

Code Block
let query = HKSampleQuery(sampleType: glucoseType!, predicate: predicate, limit: 5, sortDescriptors: nil) { (query, results, error) in
for result in results as! [HKQuantitySample] {
let bloodGlucose = result.quantity.description
let bloodGlucoseItem = HealthDataItem(endDate: result.endDate, value: String(bloodGlucose), startDate: result.endDate, type: .bloodGlucose)
let healthData = [bloodGlucoseItem]
do {
let data = try JSONEncoder().encode(healthData)
let json = String(data: data, encoding: String.Encoding.utf8)
print("json data:", json as Any )
resolve(json)
} catch {
//error handling
}
}
}

Console:

Code Block json data: Optional("[{\"value\":\"9 mg\\/dL\",\"endDate\":635308200,\"startDate\":635308200,\"type\":\"bloodGlucose\"}]")
json data: Optional("[{\"value\":\"4 mg\\/dL\",\"endDate\":635311800,\"startDate\":635311800,\"type\":\"bloodGlucose\"}]")