<<Disclaimer: Verify this information before applying it to your situation.>>

Many thanks to Amber Lee for her response to my question about whether
mono and di-glycerides are GF when they appear in "wet" foods.  Her
response was so informative I have not attempted to summarize it, but it
is reproduced it below

The Celiac Disease Foundation (CDF) and the Gluten Intolerance Groups of
North America (GIG) have an excellent updated diet guide for Celiac
Disease (CD) which recommends checking the source before eating a
product containing mono- and diglycerides (in dry products only).

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I asked the GIG in an e-mail why mono- and diglycerides were considered
questionable and this was the reply (bonus points to the GIG for sharing
the source of their information):

Mono and Diglycerides are a paste (wet) when the are manufactured. When
I spoke with the companies making them, they indicated they are safe as
they are. When they are put into a liquid or wet product (like ice
cream) there is no need to do anything to them. (A wet product added to
a wet product).  So in liquid or wet products they are not altered. When
you add them to a dry product, they must be "dried" (so to speak) in
order for them to mix well. So in products like hot chocolate mix, an
anticaking or flow agent is added by the company making the chocolate
mix. This agent can be any number of products...usually corn starch is
used, but it could be wheat.  Flow and caking agents are not always
declared on products.

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     Here is what I learned when I talked with a food scientist at
Stephen's Gourmet Cocoa.  Stephen's purchases their mono- and
diglycerides from their dairy supplier.  It comes in a blend with milk
powder.  Stephen's cocoa is gluten free and all of the ingredients used
in Stephen's recipe are declared individually.  This is, of course, only
one example of the use of dry mono- and diglycerides.

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     The Code of Federal Regulations (CFR Title 21 Sec.101.100(3))
declares that if an ingredient has no technical function in the finished
product AND is present in *insignificant* amounts, then that ingredient
does not have to be declared on the statement of ingredients.

     In a notice to manufacturers (read it at
http://vm.cfsan.fda.gov/~lrd/allerg7.html), the Food and Drug
Administration (FDA) asked food manufacturers to declare any wheat used
as processing aids.  Due to information provided by the FDA, the Food
Allergy Network, and others, most manufacturers are aware that
undeclared wheat is a problem.

     I personally consider mono- and diglycerides safe for celiacs.
However, it may not be a big issue either way since it is probably a good
idea to check with the manufacturer before consuming any highly processed
food.

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     The Code of Federal Regulations (Title 21 Sec 184.1505(a)) defines
Mono- and Diglycerides.

Mono- and diglycerides consist of a mixture of glyceryl mono- and
diesters, and minor amounts of triesters, that are prepared from fats or
oils or fat-forming acids that are derived from edible sources. The most
prevalent fatty acids include lauric, linoleic, myristic, oleic,
palmitic, and stearic. mono- and diglycerides are manufactured by the
reaction of glycerin with fatty acids or the reaction of glycerin with
triglycerides in the presence of an alkaline catalyst. The products are
further purified to obtain a mixture of glycerides, free fatty acids,
and free glycerin that contains at least 90 percent-by-weight glycerides.

You can read and search an online copy of the CFR at
http://www.access.gpo.gov/cgi-bin/cfrassemble.cgi?title=200021