Photolysis of peracetylated D-glucopyranosylidene diazide in the presence of acrylonitrile in excess leads to new isomeric spiro C-1 cyclopropanic sugars (65% combined yield). Such structures, thus readily accessible by a new route which probably involves the addition of carbenic intermediates to an electrophilic alkene, have been identified by NMR investigations. In particular, the1H NMR spectra show that the location and the orientation of the cyano substituent on the cyclopropyl ring can be easily established by way of the deshielding effect (0.2 - 0.3 ppm) which is induced on a sugar ring proton attached at C-2, C-3 or C-5. In order to unambiguously identify the obtained spirosugars, the crystal structure of one of them was determined by X-ray analysis. C17H21NO9, orthorhombic P212121, a=9.093(1), b=9.933(1), c=21.588(3) Å, Z=4, R=0.041 for 1645 unique observed reflexions.