Influence of two guar preparations on glucose and insulin levels during a glucose tolerance test in healthy volunteers.

Dietary fiber deficiency may be alleviated with an increase in fiber-rich foods or fiber in the form of guar. The efficacy of a solid guar preparation and a liquid form on glucose and insulin levels during a glucose tolerance test in 12 healthy volunteers was examined. The first half of the study tested the efficacy of a new guar preparation (GU-052, Steigerwald, Darmstadt, Germany). Six volunteers ingested 75 glucose and 12 g guar mixed in 450 ml water. The other 6 received the same drink without guar. Blood was withdrawn for the determination of glucose and insulin before ingesting the glucose solution and after 15, 30, 45, 60, 90, 120, 180, 210 and 240 min. One week later the groups were crossed over. The second half of the study tested the efficacy of GU-052 against a solid preparation consisting of 5 g guar and 1.13 g additive (Glucotard, Boehringer, Mannheim, Germany). Volunteers receiving GU-052 with the glucose drink showed no increase in plasma glucose. Volunteers without GU-052 reached a maximal plasma glucose value of 6.66 +/- 1.30 mmol/l 30 min after glucose ingestion from an initial value of 5.28 +/- 0.40 mmol/l. A second smaller peak was observed 120 min after glucose ingestion. A 2.5-fold increase from 16.17 +/- 4.30 to 40.10 +/- 19.00 microIU/ml in insulin concentration occurred in the volunteers ingesting GU-052, whereas a 6-fold increase from 19.33 +/- 12.20 to 114 +/- 48.8 microIU/ml insulin occurred in the volunteers without GU-052. A second peak in insulin at 120 min which occurred in the volunteers without GU-052 was not apparent when the volunteers ingested GU-052. The comparison of GU-052 and Glucotard showed that GU-052 maintained the glucose level, whereas Glucotard allowed the plasma glucose to reach 6.67 +/- 0.98 microIU/l. The increase in insulin was not as great with GU-052 as with Glucotard. This study shows that guar suppresses glucose and insulin levels during a glucose tolerance test. The guar form influences the efficacy.