You may have a claim under the Americans With Disabilities Act.

The ADA prohibits covered employers from discriminating against an individual with a disability, provided the person is capable of performing the essential functions of the job without an accommodation, or with a reasonable accommodation. The ADA also requires employers to provide a reasonable accommodation to a disabled individual. One common problem employees face in ADA cases is understanding that the definition of "disability" in the ADA is different than one might expect. The ADA considers a "disability" to be a physical or mental impairment; that substantially interferes with one or more major life activities.

Proper functioning of a bodily system is considered a major life activity.

If you have an ADA disability, or have a history of having such a disability, or even if you believe your employer perceives you to be disabled, you may have a claim under the ADA. Like all other federal anti-discrimination statues, the ADA requires you to file a "charge of discrimination" with the Equal Employment Opportunity Commission in order to pursue your claim against your employer.

You need to talk to an employment law attorney to get definitive advice.

What type of job did you apply for with this company? Unless having a normal blood sugar level is a bona fide requirement of the job, it sounds like a case of discrimination based upon perceived disability.