Ghrelin Growls at Glucose Tolerance

Regular readers of these pages probably recall that the hormone ghrelin, released largely from the stomach, is a key regulator of hunger and energy metabolism.

A recent study by Jenny Tong and colleagues from the University of Cincinnati, published in DIABETES, now shows that ghrelin also plays an important role in suppressing the insulin response to a glucose load.

In order to examine the effect of ghrelin on glucose metabolism, the researchers infused ghrelin at different doses (0.3, 0.9 and 1.5 nmol/kg/h) in 12 healthy participants (8 male/4 female). In addition, they performed an intravenous glucose tolerance test and measured insulin response.

Although ghrelin infusion did not alter fasting plasma insulin or glucose, it did result in a dose-dependent suppression in the insulin release to the acute glucose load.

As the authors point out:

“This is a robust proof-of-concept study showing that exogenous ghrelin reduces glucose-stimulated insulin secretion and glucose disappearance in healthy humans.”

Interestingly, ghrelin levels are markedly reduced in patients who undergo sleeve gastrectomies or gastric bypass surgery, and this finding may explain why, in many cases, these operations so dramatically improve diabetes.

As I have said before, bariatric surgery is really endocrine surgery – and we have yet to fully understand exactly how it works.

As readers will also readily appreciate, perhaps finding a drug that blocks ghrelin may provide a new treatment not just for obesity but also for diabetes.

Edmonton, Alberta

Hat tip to Andrey for bringing this paper to my attention.

Tong J, Prigeon RL, Davis HW, Bidlingmaier M, Kahn SE, Cummings DE, Tschöp MH, & D’Alessio D (2010). Ghrelin suppresses glucose-stimulated insulin secretion and deteriorates glucose tolerance in healthy humans. Diabetes, 59 (9), 2145-51 PMID: 20584998