The involved team was able to find that a a protein called peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is important in the process and the finding was believed to have explained the high incidence of diabetes and hypertension in obese individuals.

From News-Bio-Medicine.org:

The team found that when given the glucocorticoid dexamethasone, mice lacking only LDLR had increased levels of insulin, fasting glucose and leptin, all signs of diabetes. The animals also became less hypoglycemic when given insulin, suggesting that they were developing insulin resistance, the precursor to diabetes. Mice lacking both LDLR and PPAR-alpha showed no signs of diabetes.

Surprisingly, dexamethasone also increased blood pressure in mice that had PPAR-alpha but not LDLR; it did not have an affect on blood pressure in mice lacking both PPAR-alpha and LDLR.

“Somehow, animals missing PPAR-alpha were protected from developing diabetes and hypertension,” Semenkovich says.

The team then replaced PPAR-alpha in the liver in mice lacking both PPAR-alpha and LDLR. The animals developed the same symptoms of diabetes and hypertension (high blood pressure) when chronically treated with dexamethasone as mice with normal levels of PPAR-alpha throughout the body.

The study appears online and in the August issue of the journal Nature Medicine. Bernal-Mizrachi led the study, in collaboration with Clay F. Semenkovich, M.D., professor of medicine and of cell biology and physiology and director of the Division of Endocrinology, Metabolism and Lipid Research, and Daniel P. Kelly, M.D., professor of medicine, of molecular biology and pharmacology and of pediatrics and director of the Center for Cardiovascular research.

It was remarked by Benjamin D. Levine, M.D., senior author of the study and director of the Institute for Exercise and Environmental Medicine at Presbyterian Hospital of Dallas, that active players tend to easily prevent the progression of pre-diabetes from becoming real diabetes by following an active lifestyle.

From News-Medical.Net:

“Perhaps by remaining fit, the players were able to prevent the progression of pre-diabetes from becoming real diabetes,” said Benjamin D. Levine, M.D., senior author of the study and director of the Institute for Exercise and Environmental Medicine at Presbyterian Hospital of Dallas. “The prevalence of obesity, using normal criteria, is really high when you look at NFL players.

“But the BMI is only a crude measure of fatness. For the athletic community it may be biased against very dense, muscular people who may have a high BMI but not as much fat. The BMI might not tell the whole story.”

This study was based on retired players from another era. The football players today are about 50 percent larger than they were a quarter of a century ago, said Levine, who is also professor of internal medicine in the Division of Cardiology at UT Southwestern. “Today, there is a lot of incentive for football players to get as big as possible through eating, extensive training or by using anabolic steroids and growth hormones. The criterion for success is that bigger is better.”

Whether current or recently retired players are at greater risk for cardiovascular events or death merits further study, given the larger body sizes of today’s NFL player, he said.

It was also found during the study that the retired National Football League (NFL) players had a significantly lower prevalence of metabolic syndrome, diabetes, hypertension, and sedentary lifestyle when compared to other men.