Suton had 18 points and was 7-for-9 from the field in the second half for the Spartans (No. 25 ESPN/USA Today; unranked AP), who set a school record for nonconference victories.
Gray had 16 points and eight rebounds in just 12 minutes of the first half. He finished with 11 boards to record his third double-double in five weeks.
Drew Neitzel scored 10 points, 8.9 below his average, but tied his career high with 12 assists and had just one turnover.
Gerald Brown scored 25 points and was 13-for-17 from the foul line for the Greyhounds (5-6). He was 5-for-17 from the field, however.
Loyola led 34-31 in the final minute of the first half, only to see the Spartans (13-2) score five quick points on a three-point play by Suton and a last-second basket by Isaiah Dahlman.
Michigan State built a 17-point lead midway through the second half, then saw that cushion trimmed to eight.
The Greyhounds matched the Spartans with 37 rebounds but shot 35.3 percent and helped Michigan State finish November and December without allowing more than 65 points.