Just wanted some opinions on what the best way to design a "vital sign" would be. The vitals I'm interested in storing are the following:

Heart Rate - 98 BPM
Weight - 188 lbs.
Blood Pressure - 77/87 Sys/Dia
Glucose - 60 mg/dl

So, my current table design is this:

VitalSignID int
ProfileID int
VitalSignTypeID int
Value varchar(50)
DateRecorded datetime
Notes varchar(2000)

the only thing I hate about this is that blood pressure has 2 "values". It's the only vital type that does. So I'm tempted to break out "Blood Measurements" into its own table that would have a "glucose", "systolic", and "diastolic" column. What I don't like about that, is that I will have a lot of null values in cases where only glucose is collected or only sys/dia is collected....

Any thoughts here that could help me make up my mind? TIA