Jannik Sinner “under monitoring” after glucose sensor spotted in training

Jannik Sinner generated a degree of concern after being seen training with a small white device attached to his left arm, identified as a glucose monitoring sensor. The world No. 1 is currently undergoing a structured performance evaluation following his Roland Garros campaign, where he experienced a significant physical and competitive drop-off.

The device is part of a monitoring protocol introduced after a series of medical assessments conducted at the San Raffaele Hospital, according to La Gazzetta dello Sport. It is designed to track blood sugar levels during training sessions, providing real-time data on how Sinner’s body responds to workload and recovery demands.

The process was initiated after his third-set collapse in Paris, where Sinner moved within reach of victory before losing 18 consecutive games against Juan Manuel Cerúndolo. The episode has been classified internally as an abnormal energy breakdown rather than a technical or tactical issue.

Sinner is now preparing for the grass-court swing in London, where he will make a single pre-Wimbledon appearance at the Hurlingham Club exhibition, alongside players including Casper Ruud and Flavio Cobolli. He is not scheduled to compete in any official grass-court tournaments before Wimbledon.

The glucose sensor is being used as part of a broader performance analysis rather than a diagnostic tool. While the device is commonly associated with diabetes management, in Sinner’s case it is strictly aimed at studying metabolic response under competitive load.

Medical and performance staff are focusing on identifying patterns linked to energy depletion during extended matches. The objective is to assess whether fluctuations in blood sugar levels correlate with the late-match decline observed in Paris.

Initial medical examinations reportedly ruled out any underlying condition. As a result, the current phase is focused on optimisation work, including potential adjustments to nutrition, supplementation, and pre-match energy management strategies.

The monitoring framework also includes cardiovascular and blood analysis, forming part of a wider effort to map physiological behaviour under stress conditions typical of Grand Slam competition.

The key reference point for the review remains the third-set sequence in Paris, where Sinner was positioned close to closing out the match before losing momentum entirely. The subsequent run of 18 consecutive lost games has been flagged as an outlier within his performance profile.

Internally, the episode has triggered a review of endurance stability in long matches, particularly on physically demanding surfaces such as clay. The focus is on whether the collapse resulted from energy mismanagement, recovery timing issues, or an acute physiological drop.

The outcome of the current evaluation will inform how Sinner structures his preparation phases heading into the grass-court season and later the US hard-court swing.

Wimbledon remains the key target, where Sinner enters as defending champion following his title win last year against Carlos Alcaraz in the final, ending the Spaniard’s run of dominance at the event.

Alcaraz is not expected to feature in this year’s Wimbledon draw in the same capacity, increasing Sinner’s status as pre-tournament favourite. However, his Roland Garros exit has already highlighted how favouritism has previously translated into unexpected volatility in performance.

Sinner continues training in Monte Carlo before travelling to London for the final stage of preparation ahead of the third Grand Slam of the season.