Try these two:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3258205/

http://www.sciencedirect.com/science/article/pii/S0939475309001859

there is also basic info in the ADA's website:

http://www.diabetes.org/diabetes-basics/prevention/pre-diabetes/diagnosis.html

and this elaborates on clamps:

http://link.springer.com/protocol/10.1007%2F978-1-59745-448-3_15

there is a nice list of indices and their formulas in this article:

http://jcem.endojournals.org/content/88/3/1019.abstract

Thank You, this is super. Much appreciated :)

Matsuda index

You can also try Intra peritoneal insulin tolerance test, but use fast acting insulin (actrapid)

I use a fast insulin sensitivity test called RIST. This test can be performed both in fast and fed state in animals and humans.

Rapid insulin sensitivity test (RIST).

Lautt WW, Wang X, Sadri P, Legare DJ, Macedo MP.

Can J Physiol Pharmacol. 1998 Dec;76(12):1080-6.

Meal-induced insulin sensitization and its parasympathetic regulation in humans.

Patarrão RS, Lautt WW, Afonso RA, Ribeiro RT, Guarino MP, Fernandes AB, Boavida JM, Macedo MP.

Can J Physiol Pharmacol. 2008 Dec;86(12):880-8. doi: 10.1139/Y08-080.

Understanding postprandial glucose clearance by peripheral organs: the role of the hepatic parasympathetic system.

Fernandes AB, Patarrão RS, Videira PA, Macedo MP.

J Neuroendocrinol. 2011 Dec;23(12):1288-95.

The rapid insulin sensitivity test (RIST) is an accuracy test for insulin sensitivity test that can performd in fasting and feeding stat. You can use it.

Ref: Fernandes AB, et al. J Neuroendocrinol. 23(12):1288-95, 2011.