Diabetes?

Hi,
I have been diagnosed with granuloma annulare recently (have had the spots for about a year and a half...interestingly they showed up just after I started a low carb diet).  I get tingling and stiffness in my hands and feet(though better now that I've lost some weight), frequent infections (respiratory, and lately vaginal area), and have a family history of diabetes.  I have been feeling MUCH better since I started the low carb diet, but my dermatologist suggested I get tested for diabetes when I was diagnosed with GA...I had suspected for a while that I may have it, but the test came back negative. Could the low carb diet be 'masking' the diabetes?  Am I actually managing it by eating low carb?
Thanks,
Trish