dex2mqtt

This script fetches latest glucose reading from Dexcom and publishes to MQTT.

Requirements

• Dexcom G6 CGM System with credentials for Dexcom Share
• node 14.4 or later
• MQTT broker

Setup

• cp .env.sample .env
• Add variables to .env
• npm install
• npm start

Schedule with cron

which node gives the path to node.

• crontab -e
• */5 * * * * cd /path/to/dex2mqtt && /path/to/node --require ./node_modules/dotenv/config index.js >/dev/null 2>&1

Home Assistant

Read values with sensor

In configuration.yml

MQTT configuration

mqtt:
  broker: <broker IP>
  port: <broker port>
  discovery: true

Sensor configuration

sensor:
  - platform: mqtt
    state_topic: 'glucose/current'
    name: Glucose
    icon: mdi:chart-bell-curve-cumulative
    unit_of_measurement: mmol/L

Change light color depending on glucose reading

In automations.yml:

  - alias: Glucose lamp color
    trigger:
      platform: mqtt
      topic: 'glucose/current'
    action:
      - service: light.turn_on
        entity_id: light.<lamp name>
        data_template:
          color_name: >
            {% if (trigger.payload|float) < 3 or (trigger.payload|float) > 15 %}
              red
            {% elif (trigger.payload|float) > 5 and (trigger.payload|float) < 10 %}
              green
            {% elif (((trigger.payload|float) - 8)|abs) < 1 %}
              greenyellow
            {% elif (((trigger.payload|float) - 8)|abs) < 2.5 %}
              yellow
            {% elif (((trigger.payload|float) - 8)|abs) < 5 %}
              orange
            {% elif (((trigger.payload|float) - 8)|abs) > 5 %}
              orangered
            {% else %}
              white
            {% endif %}