This is the A1C/blood glucose chart that my healthcare provider uses. It is the most recent one of know of, being based on a 2008 study.

A1C Chart & Calculator ADAG
A1C-Derived Average Glucose (ADAG)
Study to define the mathematical relationship between HbA1c and eAG.

Translating the A1C Assay Into Estimated Average Glucose Values
Diabetes Care 31:1473–1478, 2008