For hyperglycaemia at least ketones would be a significant marker. In sufficient concentration they even have a characteristic smell detectable by humans. So, c

For hyperglycaemia at least ketones would be a significant marker. In sufficient concentration they even have a characteristic smell detectable by humans. So, creating a sensor that measures ketone concentration shouldn't be too difficult. Hypoglycaemia is more difficult to diagnose because apart from the actual blood glucose level there's no definite symptom that doesn't occur with other conditions as well (typical symptoms include headaches, dizziness, confusion, high pulse rate).