Background: Continuous glucose monitoring (CGM) devices, with their 1-5min measurement interval, allow blood glucose concentration (BG) dynamics to be captured more frequently and less invasively than traditional BG measures. One cohort CGM could provide insight is athletes. This study investigates what impact their heightened energy expenditure and dietary intake may have on their ability to achieve optimal BG. Methods: Ten sub-elite athletes (resting HR<60bpm, training>6hrs per week) were recruited. Two Ipro2 CGM devices (Medtronic Minimed, Northridge, CA) were inserted into the abdomen and remained in place for ~6days. Time in band was calculated as the percentage of CGM BG measurements with in the 4.0 - 6.0mmol/L. Fasting glucose was calculated using CGM calibration BG measurements and postprandial glucose response was also calculated using the CGM values. Results: 4/10 athletes studied spent more than 70% of the total monitoring time above 6.0mmol/L even with the 2hour period after meals is excluded. Fasting blood glucose was also in the ADA defined pre-diabetes range for 3/10 athletes. Only one participant spent substantial time below 4.0mmol/L which was largely due to significantly lower energy intake compared to recommendations. Conclusions: Contrary to expectations high BG appears to be more of a concern for athletes then low BG even in those with the highest energy expenditure and consuming below the recommended carbohydrate intake. This study warrants further investigation on the recommended diets and the BG of athletes to better determine the causes and impact of this hyperglycaemia on overall athlete health.