ReGlucose Tolerance Test with Concurrent Insulin levels.
The assay of serum for insulin levels requires critical laboratory handling procedures. See information below on this page and also in the links below.
But the performance of insulin assays concurrently with an Oral Glucose Tolerance Test (OGTT) provides information on the ability of the pancreas to respond to the entry of glucose to the blood stream. This response in any individual is governed by many factors; eg i)heredity, ii)intra-uterine hormonal environment before the individual's birth, iii)as a neonate the insulin levels in the mother's breast milk*, iv)diet, v)exercise, vi)body mass with feedback from PC-1 produced in the intra-abdominal fat, vii)endocrine changes associated with puberty, menstruation, pregnancy, menopause, vii)endocrine changes associated with stress of any kind, whether physical or surgical trauma, infection or emotion.
Until the doctor understands the above, he should not venture to comment on the value of insulin assays!!!!!
References to substantiate the above will be found if you search my numerous pages on the www. Experimental work to support the buccal absorption of insulin in the breast* fed infant is awaiting publication. I will add those references as time permits. Dr Allen E Gale Consultant Physician & Adelaide Aerobiology Laboratory, South Australia 0620hours October 11, 2000
Explaining the importance of correct handling procedures for insulin assays to laboratories who have strict budget constraints has proved a sisyphean task! Now that there is accelerating interest in insulin assays, I reproduce correspondence from the manufacturer forthwith:-
Subject: Insulin Storage Conditions
Date: Wed, 30 Jul 1997 19:36:23 -0500
I am the Product Manager for Immunodiagnostics at Abbott which includes our Insulin assay. FW* has forwarded to me your E-Mail with your concerns at the apparent poor storage conditions of Insulin specimens . The case studies you included certainly highlight the importance of laboratories maintaining strict storage and transport conditions.
I would like to point out that in our package insert there is considerable attention given to the storage conditions of Insulin specimens. Of most relevance are the points " All specimens should be stored at -20C or colder" and "The freeze thaw cycles should be avoided". This would seem to concur with your considerable first hand experience on this matter. I am not able to say whether the other suppliers of Insulin reagents have the same instructions.
I will be sending our Insulin Package Insert to you for your records. This key point has been noted and communications with our customer base will be initiated informing them of the importance of maintaining correct and stated storage conditions for Insulin specimens as per our Package Insert instructions . I will also be forwarding to you this notice.
Dr Gale, I appreciate your concern and you drawing to our attention this deficiency in laboratory Quality Control procedures. Abbott is committed to pursuing the strict adherence of our Package Insert instructions and please do not hesitate in contacting me on this or any matter that Abbott Diagnostics may be able to assist.
Product Manager- Immunodiagnostics
*Names on file