The Diabetes and Obesity Link
Dr. Josephine Carlos-Raboca
Makati Medical Center

Obesity is the accumulation of excess body fat. Body fat is normally 12-20% in men and 20-30% in women. As body fat increases, the risk of developing illness goes higher. Body fat is measured by getting the Body Mass Index (BMI) calculated by weight in kilograms/height in meter squared. The other useful measurements are waist to hip ratio and the waist circumference. In Caucasians, a BMI >25 is considered overweight, >30 is obese. In Asians, a BMI >23 is overweight, >28 is obese.

Health risks associated with obesity are stroke, hypertension, diabetes mellitus, some cancers, gout, gallbladder disease, arthritis, and heart disease. The higher the BMI is the higher the risk.


How Obesity Leads to Diabetes Mellitus

Progression of weight gain is accompanied by worsening insulin resistance, which is the early stage of Type 2 diabetes. This means that insulin cannot bring about glucose utilization by the muscle as much as it should, thereby causing more insulin to be released by the a cells of the pancreas. More insulin in the blood called hyperinsulinemia is bad as it may promote atherogenesis or vessel wall thickening, which can block blood flow to vital organs like the heart and the kidney. Too much insulin can also lead to water and salt retention and activation of adrenalin leading to increased blood pressure or hypertension. Too much insulin production from cells therefore is not good as it seems to look like and eventually may lead to a cell failure signaling the beginning of diabetes mellitus Type 2. Fat amount in a cell can cause a decrease in insulin secretion.

Studies show that the enzyme called glycogen synthase which enables the glucose to be stored in the skeletal muscle as glycogen is impaired in both obese and Type 2 diabetes mellitus.

Insulin needs to attach to receptors found at the membrane of the cell. As the insulin attaches to the receptor, messengers like the protein enzyme kinases and the insulin substrate receptor 1 are activated. This leads to the movement of glucose transporters called Glut 4 from the inner part of the cell to the cell membrane. This protein will then transport the glucose into the cell. When there is too much fat, this process is blocked. One of the factors responsible is a small protein called tumor necrosis factor alpha released by fat.

Insulin resistance brings about the break down of fat stores to free fatty acids. When too many fatty acids are present, the muscle tends to use these more than glucose energy source so the blood glucose rises. In the liver, insulin resistance drives the liver to produce glucose rather than store it as glycogen.

It is therefore advisable to reduce weight to reduce health risks like diabetes mellitus Type 2. It has been shown that as little as 10% body weight loss has beneficial effects on health risks such as improved diabetes control, hypertension and lipid disorder. In patients with diabetes, as little as 5% of weight loss can lead to substantial improvement. Each kg of weight loss in the first year is associated with 3-4 month increase in survival. For those who are not yet obese, making a conscious effort to avoid getting fat will lessen the chance of developing diabetes.