A new update will bring significant changes to the Fitbit Charge 4 and the Fitbit app, including the introduction of manual blood glucose monitoring.

The latest software, which is rolling out to users over February, doesn't mean that Fitbit devices can perform invasive tracking, but it does provide those with diabetes or other medical conditions a place to log and view their blood sugar readings.

Since users can set personal high and low ranges, the idea appears to be to help users recognise patterns in their levels by logging readings over time, and perhaps seeing how sleep, activity or meals affect them.

It's not the only big health change coming, either, with some of the Health Metrics features previously hidden behind the Fitbit Premium paywall now becoming free for users to explore. 

For those who have a Fitbit Versa 2, Charge 4 or Inspire 2, graphs showing data on Breathing Rate and Heart Rate Variability will be available for the first time. And though it's only a week's worth of data - rather than the month available to Fitbit Premium users - it's a welcome addition for casual users who want a bit more to dive into. 

Premium users still get a treat from the new update, though, with Health Metrics now offering up personal ranges to help untangle some of the data being presented. For big rises or falls in resting heart rate, for example, this adds a much-needed bit of context to typical figures.

Outside of the health-focused changes to the Fitbit app, the company has also found the time to bolster the Charge 4. 

Skin temperature readings have now been added, something previously found only on the Fitbit Sense, while blood oxygen readings can now also be accessed directly from the device, rather than solely in the app's Estimated Oxygen Variation graph. 

At least from a health monitoring perspective, these changes bring the company's classic tracker in line with its most premium devices, giving them a well-supported alternative to a smartwatch. However, we expect the Versa 3 to catch up pretty quickly, perhaps even in its next device update.