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# HKMetadataKeyBloodGlucoseMealTime

A key that indicates the relative timing of a blood glucose reading to a meal.

```
let HKMetadataKeyBloodGlucoseMealTime: String
```

## Discussion

Set this key on a [`bloodGlucose`](/documentation/HealthKit/HKQuantityTypeIdentifier/bloodGlucose) sample. Set it’s value to an <doc://com.apple.documentation/documentation/Foundation/NSNumber> object containing a [`HKBloodGlucoseMealTime`](/documentation/HealthKit/HKBloodGlucoseMealTime) value.Medical professionals can use the relative meal time to help determine the acceptable range for a blood glucose reading. If your app requires more precise timing or additional information about the meal’s composition, create  samples to record those details (for example, a [`dietaryCarbohydrates`](/documentation/HealthKit/HKQuantityTypeIdentifier/dietaryCarbohydrates) sample with the exact meal time).

## Topics

### Valid Values

[`HKBloodGlucoseMealTime`](/documentation/HealthKit/HKBloodGlucoseMealTime)

Constants indicating the timing of a blood glucose sample relative to a meal.


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