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Diabetes

Diabetes Mellitus is a chronic disease where the body does not make or use insulin* properly, resulting in having too much glucose in the blood. The World Health Organization recognizes 3 main forms of diabetes mellitus: type 1, type 2, and gestational diabetes (occurring during pregnancy), which have different causes and population distributions. While all forms are due to the beta cells of the pancreas being unable to produce sufficient insulin to prevent hyperglycemia, the causes are different.

[*Insulin is a hormone that helps the body to control the level of glucose in the blood]

Types of Diabetes Mellitus

Type 1: Insulin-Dependent Diabetes

Persons with Type 1 diabetes cannot control their blood sugar properly because their pancreas produces little or no insulin. Type 1 diabetes is usually due to autoimmune destruction of the pancreatic beta cells. The body’s own immune system mistakenly destroys the insulin producing cells in the pancreas. As a result, glucose builds up in the blood instead of being used for energy. Persons with Type 1 diabetes need insulin injections to control their blood sugars. Although it usually happens to young people before the age of 30 (most often during childhood or their teens), it can also occur in older adults but less commonly. The cause of Type 1 diabetes remains unknown. It is not preventable and it is not caused by eating too much sugar.

Type 2: Non-insulin Dependent Diabetes

About 80% of all persons with diabetes belong to this group. They can produce insulin, but their body does not use it effectively. Type 2 diabetes mellitus is due to insulin resistance or reduced insulin sensitivity, combined with reduced insulin secretion. The defective responsiveness of body tissues to insulin involves the insulin receptor in cell membranes. In the early stage the predominant abnormality is reduced insulin sensitivity, characterized by elevated levels of insulin in the blood. At this stage hyperglycemia can be reversed by a variety of measures and medications that improve insulin sensitivity. As the disease progresses the impairment of insulin secretion worsens, and therapeutic replacement of insulin often becomes necessary.

There are numerous theories as to the exact cause and mechanism in type 2 diabetes. Central obesity (fat concentrated around the waist in relation to abdominal organs, but not subcutaneous fat) is known to predispose individuals for insulin resistance. Abdominal fat is especially active hormonally, secreting a group of hormones called adipokines that may possibly impair glucose tolerance. Obesity is found in approximately 55% of patients diagnosed with type 2 diabetes.

Type 2 diabetes is usually first treated by increasing physical activity, decreasing carbohydrate intake, and losing weight. These can restore insulin sensitivity even when the weight loss is modest, for example around 5 kg, most especially when it is in abdominal fat deposits. It is sometimes possible to achieve long-term, satisfactory glucose control with these measures alone. However, the underlying tendency to insulin resistance is not lost, and so attention to diet, exercise, and weight loss must continue.

Gestational diabetes

Gestational diabetes mellitus (GDM) resembles type 2 diabetes in several respects, involving a combination of inadequate insulin secretion and responsiveness. It occurs in about 2%?5% of all pregnancies and may disappear after delivery. Gestational diabetes is fully treatable but requires careful medical supervision throughout the pregnancy. About 20%?50% of affected women develop type 2 diabetes later in life. Untreated gestational diabetes can damage the health of the fetus or mother. Risks to the baby include macrosomia (high birth weight), congenital cardiac and central nervous system anomalies, and skeletal muscle malformations.

Pre-diabetes

Pre-diabetes is a condition that occurs when a person's blood glucose levels are higher than normal but not high enough for a diagnosis of type 2 diabetes.

Who gets diabetes?

About 9% of the adult population in Singapore have diabetes. Diabetes can affect people of any age or race. However, 90% of people with diabetes are over 40 years old.

Some risks of diabetes mellitus include:

• Family history
• Overweight
• More than 40 years of age
• Pregnancy
• Exposure to a trigger mechanism (a virus or chemical substance)

References:

1. World Health Organisation Department of Noncommunicable Disease Surveillance (1999). Definition, Diagnosis and Classification of Diabetes Mellitus and its Complications

2. Diabetic Society of Singapore

by Ruth Tay
Certified Nutrition Consultant