A wide scatter of absolute levels of pancreas triacylglycerol has been reported, with a tendency for higher levels in people with diabetes (57). This large population study showed overlap between diabetic and weight-matched control groups. These findings were also observed in a more recent smaller study that used a more precise method (21). Why would one person have normal β-cell function with a pancreas fat level of, for example, 8%, whereas another has type 2 diabetes with a pancreas fat level of 5%? There must be varying degrees of liposusceptibility of the metabolic organs, and this has been demonstrated in relation to ethnic differences (72). If the fat is simply not available to the body, then the susceptibility of the pancreas will not be tested, whereas if the individual acquires excess fat stores, then β-cell failure may or may not develop depending on degree of liposusceptibility. In any group of people with type 2 diabetes, simple inspection reveals that diabetes develops in some with a body mass index (BMI) in the normal or overweight range, whereas others have a very high BMI. The pathophysiologic changes in insulin secretion and insulin sensitivity are not different in obese and normal weight people (73), and the upswing in population rates of type 2 diabetes relates to a right shift in the whole BMI distribution. Hence, the person with a BMI of 24 and type 2 diabetes would in a previous era have had a BMI of 21 and no diabetes. It is clear that individual susceptibility factors determine the onset of the condition, and both genetic and epigenetic factors may contribute. Given that diabetes cannot occur without loss of acute insulin response to food, it can be postulated that this failure of acute insulin secretion could relate to both accumulation of fat and susceptibility to the adverse effect of excess fat in the pancreas.

Normally, blood glucose levels are tightly controlled by insulin, a hormone produced by the pancreas. Insulin lowers the blood glucose level. When the blood glucose elevates (for example, after eating food), insulin is released from the pancreas. This release of insulin promotes the uptake of glucose into body cells. In patients with diabetes, the absence of insufficient production of or lack of response to insulin causes hyperglycemia. Diabetes is a chronic medical condition, meaning that although it can be controlled, it lasts a lifetime.