The Marathon County jury deliberated nearly four hours before finding Leilani Neumann, 41, of Weston guilty of second-degree reckless homicide in the death of 11-year-old Madeline Kara Neumann, the Wausau Daily Herald reported.
The girl's father, Dale Neumann, is to go on trial on the same charges in July.
Leilani Neumann's attorney said the verdict, which carries a prison sentence of up to 25 years, will be appealed, the Daily Herald said. No date was set for sentencing.
The Neumanns relied on prayer to try to cure their daughter of diabetes and she died March 23, 2008, from complications of the disease.
Texas principal bans speaking Spanish, stirs controversy
Caroline Berg Eriksen: Soccer player's wife triggers debate with post-birth selfie