Obesity's Link to Type 2 Diabetes Not So Clear-Cut
Most participants developed condition after being overweight for years, not after large recent gain
From this group, the researchers found three distinct patterns of overweight and obesity. The first, and by far the largest group, was dubbed the "stable overweight." Members were overweight throughout the study, but had a relatively stable BMI.
In addition to a stable weight in this group of 604 people, the researchers only saw a slight worsening of their insulin resistance in the five years before the type 2 diabetes diagnosis.
Another group -- with just 15 people -- was called the "progressive weight gainers." They gained weight throughout the study and saw a large increase in their insulin resistance in the years leading up to their diagnosis.
The third group was dubbed the "persistently obese" and 26 people fell into this category. These folks were severely obese throughout the study. They didn't experience significant insulin resistance. However, some of their insulin-producing cells in the pancreas (beta cells) died off.
The researchers also looked at other health factors, such as blood pressure and cholesterol levels, and found differences between the groups, but none to clearly define who might develop type 2 diabetes and who might not.
"This study shows us again that diabetes and obesity are very complex, and the development of type 2 diabetes is not as simple as we think. Not all patients with diabetes are obese, and not all obese are diabetics," said Dr. Joel Zonszein, director of the clinical diabetes center at Montefiore Medical Center in New York City.
Zonszein said that there are genetic factors involved in the development of type 2 diabetes, and the type of fat someone has matters, too. People who have less brown fat (considered a good type of fat) and carry more weight around the middle are generally more likely to get type 2 diabetes, according to Zonszein.
But, he added that the exact trigger for the development of type 2 is still "the six-million-dollar question. We can't point to exactly what causes type 2, but we do know that it's not good to become obese," he said.
Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York City, also pointed out that a combination of factors lead to the development of the condition. "But we do know that excess weight is related to an increased risk of type 2 diabetes," he said.