Ketone monoester intake tempers blood glucose levels

In patients with impaired glucose tolerance (IGT), taking ketone monoesters (KMs) before an oral glucose tolerance test (OGTT) lowers the area under the curve for glucose, a new Japan study has found.

The study included nine IGT patients (aged 48–62 years; five females). Participants were made to fast overnight, after which they underwent a 75-g OGTT for 180 minutes with and without KM ingestion. Tests were performed on separate days and with randomized, cross-over design.

Glucose concentrations at 60, 90, and 120 minutes after ingestion were all significantly lower when the OGTT was performed with vs without KM ingestion. In turn, the primary outcome of AUC-glucose during OGTT was likewise lower when patients took KM.

This improvement in AUC-glucose appeared to be driven by a spike in insulin levels during the first half of the test, according to the researchers. At 30 and 90 minutes after ingestion, insulin and AUC-insulin were both significantly higher when testing was performed with vs without KM. C-peptide levels at any point during testing had no clear impact on this insulin spike.

In terms of secondary outcomes, D-beta-hydroxybutyrate (βHB) levels increased immediately during OGTT with KM, peaking at 90 minutes, after which the concentration remained stable. This pattern of change was not observed in the no-KM condition, such that βHB was significantly higher at all OGTT time points following KM intake. The resulting AUC-βHB was likewise greater in the KM condition.

“[O]ur data demonstrated that reduced AUC-glucose in the KM condition was associated with elevated insulin levels during the first half of OGTT,” the researchers said. “Taken together, the KM-induced increase in circulating insulin levels during the first half of OGTT may have contributed to reduced glucose levels during the OGTT procedure.”