Disorders of Blood Sugar

Roberto Victor Illa, M.D.



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Dear referring practitioner:

Before we see a new patient, we always order certain laboratory tests which guide us in our assessment. To facilitate timely evaluation of your patient, please order the tests below in advance of the referral so that when we do meet with your patient we are better able to make a correct diagnosis and provide the appropriate treatment.

Thank you.
Roberto V. Illa, M.D.
Disorders of Blood Sugar




What Tests do we use?

1. C-Peptide.

2. Comprehensive panel. (This is mainly for the eGFR).

3. GTTID(G). This is a modified glucose tolerance test with sampling for insulin and glucagon added. Patient begins the test fasting. Instead of glucola, the patient can eat whatever he/she wants for a meal. Times of sampling are:
  • Fasting
  • 1/2 hr
  • 1 hr
  • 2 hrs
  • 3 hrs
  • 4 hrs

The GTTID(G) is available from Quest Labs and Hunter Labs.

4. 25 OH Vitamin D level: Low vitamin D is correlated with abnormalities of blood sugar and cardiovascular complications.

5. The Hemoglobin A1c is optional, as it does not assist in making a diagnosis. All disease states causing blood sugar disorders can have an elevated HgbA1c (Type 1 diabetes mellitus, Type 2 diabetes mellitus, Nesidioblastosis, Hypothalamic hypoglycemia, all four solid tumors of the abdomen producing insulin or insulin-like substances). A high A1c does not provide a differential diagnosis, while a normal A1c does not preclude the presence of these disorders.

Reason for referral

Please provide us with a brief history of the problem.

Also, please indicate any of the following:

  • Type 1 diabetes?
    • History of ketoacidosis?
    • History of hyperosmolar state?
  • Type 2 diabetes?
    • Poorly controlled?
    • High HgbA1c?
    • Non-compliant?
  • Hypoglycemic episodes?
  • Loss of consciousness?
  • Seziures?
  • Recent hospitalization?
  • Non-contrast brain MRI within the past 5 years?
    • Where?
  • Congestive heart failure?
  • Pacemaker or metal device in body?