Any line manager worth his or her salt not only looks after the day to day management of the staff but also keeps a distant eye on their personal life and health too. This is not from an intrusive point of view, but understanding the morale of your staff is an important part of motivation.
Even if the company offers private medical insurance you cannot take it for granted that your staff are fit and healthy and if they start to take sick days off work for any reason it could be the symptom of an underlying cause which you should investigate discretely with them.
Do not pry into their private life but encourage them to talk openly to you so that you have an understanding of why they are taking time off work – and costing the company money.
With some staff it will be purely physical and explained by a recurring illness, for which they will be able to produce a doctor's certificate, but with others it could be a lack of motivation or worse which is causing them to miss work occasionally.
Be firm but understanding and try to encourage them to resolve whatever is the underlying issue behind their sick days as it is costly in loss of work as well as setting a bad example to other members of staff.
