By injecting a hormone produced by fat and other tissues into mice, researchers report in the November Cell Metabolism that they significantly lowered blood sugar levels in normal and obese mice.
The findings suggest that the hormone known as apelin might be a promising target for managing insulin resistance and type 2 diabetes.
Insulin resistance, in which normal amounts of insulin are insufficient to lower blood sugar (glucose) levels, is a precursor to diabetes.
"The effects of apelin appear to be similar to insulin," although they operate in different ways, said Isabelle Castan-Laurell of Institut National de la Santé et de la Recherche Médicale and Université de Toulouse.
Earlier studies had suggested a link between apelin and insulin, Castan-Laurell said. Apelin levels were shown to parallel insulin levels in mice and humans. Apelin levels in the blood also rise in those who are obese and in those with type 2 diabetes.
Those findings led the researchers to suspect that apelin and insulin might have other similarities.
Now, they show that acute intravenous injections of apelin have a powerful blood sugar-lowering effect on mice. They also show evidence that apelin stimulates muscle and fat tissue to take up glucose from the bloodstream by stimulating a known glucose transport pathway. Specifically, apelin activates a pathway including an enzyme called AMP-activated protein kinase (AMPK), which plays a pivotal role in the control of skeletal muscle glucose and the metabolism of fatty acids.
Moreover, they showed that apelin treatment restores glucose tolerance and improves glucose uptake in mice that are obese and insulin resistant.