In a study published in Circulation Research, a team of scientists described a series of studies designed to determine the relationship between insulin, fats, and the vascular system. The study has identified a new pathway in which the cells lining the blood vessels, i.e., endothelial cells, drive the metabolism. The findings of the study suggest that vascular dysfunction leads to undesirable metabolic changes that cause diabetes, a reversal of the previously known scientific dogma. 

Dr. Thomas J. Beatson, Jr., Professor of Medicine in the Field of Diabetes at Harvard Medical School, stated that the idea has always been that in people with diabetes and insulin resistance, white fat and inflammation cause dysfunction in the blood vessels, leading to the prevalence of heart disease, eye disease, and kidney disease. But, the findings of the study showed that blood vessels have a major controlling effect on cause-effect balance, and that was not known previously. He further added that along with its association with blood vessel abnormalities, diabetes is also associated with an undesirable decrease in brown adipose tissue.

In the study, a series of experiments were conducted using a mouse model of diabetes. The research team observed that mice engineered with enhanced insulin sensitivity only in the blood vessels weighed less than control animals, even when fed a high-fat diet. The teams further investigation revealed that insulin signals endothelial cells in the blood vessels to produce nitrous oxide, which in turn triggers the production of brown fat cells. In terms of insulin resistance, endothelial cells produced less nitrous oxide, a factor known to raise the cardiovascular risk that causes a drop in brown fat production. Brown fat plays an integral role in regulating the bodys weight and metabolism. The study also suggested that smaller brown fat stores could be a risk factor for, not a symptom of, diabetes. 

(Source: https://www.hindustantimes.com/lifestyle/health/relationship-among-diabetes-fat-and-cardiovascular-disease-study-101659761716181.html )