Brief Answer:
more frequent blood sugar monitoring required
Detailed Answer:
Dear Friend
Thanks for writing to us.
Chondroflex contains supplements like Chondrotin and 
glucosamine, which are helpful in 
osteoarthritis. However, there is no clear-cut medical evidence of their benefit in osteoarthritis.
About your concern that a diabetic can take it or not, I would like to tell you that glucosamine has been implicated to worsen blood sugar levels in patients with 
diabetes , but again there is no clear cut evidence. 
The mechanism by which glucosamine is hypothesized to affect blood 
glucose involves the roles of glucosamine and the hexosamine biosynthesis pathway in the regulation of glucose transport.
Many studies deny this finding in their patients. 
There is no clear-cut well established evidence supporting this hypothesis, but, I would recommend a frequent blood sugar monitoring, if she takes this supplement.
She can be started on this supplement, with a fresh glycosylated 
hemoglobin value, which can be repeated after 3 months and can be compared.
I hope I am able to solve your query, still if you have any query you can ask me.