I would add to Paul's post, As he says you need them to check ketones if you are ill. This is very important if you are vomiting or have diarrhoea, even when your glucose levels are fairly low. Occasionally when ill, people can develop DKA at lower glucose levels,
It is rare (rare enough that case studies get written about it ) but there have been a couple of people on here who have had DKA at relatively normal levels in such circumstances. If you test when you are ill, you can hopefully intervene before it gets that far by giving extra insulin.
You do though need to know what to do before you are ill. Check with your nurse but these are useful sick day rules (as per DAFNE)
http://www.diabetes-support.org.uk/info/?page_id=141
This is what the writers of one recent case study ( a poorly controlled adolescent who had DKA with a level in the 6s) says.
Although euglycemic DKA is rare, low caloric intake, starvation, persistent vomiting, and pregnancy can be contributory factors in its development (2,5,9,13). Fasting frequently occurs during the development of DKA either as a result of an underlying condition such as infection or as a result of the worsening of ketoacidosis per se. Fasting leads to reduced carbohydrate intake, to decreased glucose production, or to increased glucose utilization. It predisposes patients with T1DM to euglycemic ketoacidosis (9,14).
You can get blood ketone strips for the Optimum xceed meter. They are expensive but have the advantage that they come foil wrapped and have a long shelf life. Urine ketone strips are much cheaper but have a short shelf life when opened.
Personally, apart from at diagnosis, I've only had ketones show up a couple of times and they weren't high. I turned down the offer of a meter for blood ketones but do have ketostix on my prescription.
