Search Observation (BG & Carbs) by parameters

A client can search for Blood Glucose (BG) and Carbohydrate intake Observations by using the GET method on the server's Observation endpoint with the following query parameters.

The Continuous Glucose Monitoring (CGM) search is documented separately because CGM readings are aggregated into compound Observations using SampledData. CGM searches MUST NOT be combined with BG or Carbohydrate searches. For CGM guidance see: CGM Observation Search.

Supported codes

The search supports the following LOINC codes:

• 32016-8 Glucose [Mass/volume] in Capillary blood
• 9059-7 Carbohydrate intake Estimated

Query Parameters

Parameter	Description	Required
subject	Patient Record ID (FHIR Patient logical id)	true
code	One of the supported codes listed above	true
date	Effective date/time range (Observation.effective[x]) (see validation below)	either date or _lastUpdated
_lastUpdated	Last updated timestamp range (Resource.meta.lastUpdated) (see validation below)	either date or _lastUpdated
page	Opaque page identifier for retrieving subsequent result pages	false
_sort	Sort by effective date: date (ascending) or -date (descending, default)	false

Date / _lastUpdated validation

The following rules apply independently to each supplied time-range parameter (date and _lastUpdated):

1. Provide exactly two repeated parameters: first with ge, second with le (e.g. date=ge...&date=le...).
2. Format: [ge|le]yyyy-MM-ddTHH:MM:SS[+|-]HH:MM.
3. The start instant must be earlier than the end instant.
4. Maximum supported search duration is 90 days.

Either date or _lastUpdated MUST be present; both MAY be present.

_sort parameter

Accepted values: date (ascending) or -date (descending). Default is descending by effective date.

Examples

Search BG Observations

curl -sS "https://${server}/fhir/r5/api/Observation?subject=${patient_id}&code=32016-8&date=ge2024-09-01T00%3A00%3A00Z&date=le2024-09-14T00%3A00%3A00Z&_sort=-date" \
  -H "client_id: ${client_id}" \
  -H "client_secret: ${client_secret}" \
  -H "org_id: ${org_id}" \
  -H "certificate: ${certificate}" | jq

Search Carbohydrate Observations

curl -sS "https://${server}/fhir/r5/api/Observation?subject=${patient_id}&code=9059-7&_lastUpdated=ge2025-09-01T00%3A00%3A00Z&_lastUpdated=le2025-09-02T00%3A00%3A00Z&_sort=date" \
  -H "client_id: ${client_id}" \
  -H "client_secret: ${client_secret}" \
  -H "org_id: ${org_id}" \
  -H "certificate: ${certificate}" | jq

Response

The server responds with a FHIR Bundle of type searchset containing matching Observation resources. Each BG or Carbohydrate Observation represents a single measurement (no aggregation). Pagination is indicated through Bundle.link entries with relation next when additional pages exist.

Error Handling

On error, an OperationOutcome is returned describing the issue (e.g., invalid date format or unsupported code).