In June 2021, the World Journal of Diabetes published results of a prospective, double-blind, randomized, controlled study evaluating the blood glucose profile after oral lactulose intake in mildly constipated, non-insulin-dependent subjects with type 2 diabetes.
Single oral doses of 20g or 30g lactulose as liquid or crystal formulation were administered and compared to water as negative control or 30 g glucose as positive control.
While the blood glucose concentration-time curves after intake of 20g and 30g lactulose were almost identical to those after water intake for both lactulose formulations ingestion of 30g glucose significantly increased all blood glucose endpoints. No differences in blood glucose response were observed between the different lactulose formulations.
Moreover, as expected lactulose increased the number of bowel movements and was generally well tolerated. (Pieber TR, et al. World J Diabetes 2021;12(6):893.)

Link to the paper: www.wjgnet.com/1948-9358/full/v12/i6/893.htm