In the past we understood only two types of Diabetes – Insulin Dependent also earlier named as Juvenile Diabetes in Young and Non-Insulin Dependent Diabetes in older people.
With the alarming rise of diabetes in India and globally, we are now seeing younger and younger diabetic patients, so the question of whether they are Type 1 or Type 2 DM is a challenge to diagnose and requires a good history, proper examination, and few investigations. We are also now classifying other types which classically do not fit into these.
Type 1 diabetes or Insulin-dependent Diabetes:
Type 1 diabetes is an auto-immune disorder in which the pancreas fails to produce insulin due to the destruction of the insulin-producing Beta ( ) cells (insulin-producing cells in specialized areas “Islet of Langerhans” in the pancreas). Unknown factors cause the formation of antibodies against pancreatic Beta ( ) cells, thus, destroying them. Blood glucose levels rise to dangerously high levels. Insulin therapy is essential for the survival of the patient.
These patients if left untreated or daily treated they may develop Ketoacidosis which is an accumulation of dangerous acids in body in the absence of insulin and sometimes may lead to coma (unconsciousness).
Type 2 Diabetes Mellitus (or T2DM or Adult-onset Diabetes):
People with type 2 diabetes are able to produce insulin in their pancreas. Many of these patients have resistance to the action of insulin due to excess body fat. The body tries to overproduce insulin to counter rising glucose. Later, insulin secretion falls as pancreatic Beta ( ) cells get exhausted.
Type 2 diabetes is linked to overweight/obesity.
Typical characteristics of Type 2 diabetes:
- Gradual onset over a period of time, sometimes without symptoms;
- Adult-onset, now also seen in age 20s and 30s;
- Strongly linked to obesity (which causes insulin action to be low; insulin resistance);
- Usually responds to lifestyle alterations, weight loss, and oral medications.
Type 2 diabetes is generally hereditary. Both parents if having the disease, there is an 85% likelihood that the child will get DM. A sign of Insulin resistance present in these patients is “Acanthosis Nigricans” which is a velvety pigmented area around the neck, axilla and creases or folds of skin. They may also have sedentary lifestyles and increased adiposity.
Gestational Diabetes (Pregnancy-related Diabetes):
Gestational diabetes is a term used for high blood glucose levels which occur only during pregnancy. Factors causing gestational diabetes include obesity, late pregnancy, family history of diabetes, previously delivering a child weighing 4 kg or more and in certain ethnic groups, including Indians. A woman with gestational diabetes may have hypertension, increased risk of miscarriages, cesarean section delivery, and diabetes later in life. Complications for the baby include; large in size, jaundice, birth defects, lung problems, and low sugar levels immediately after birth. Gestational Diabetes is best treated with insulin.
Latent Autoimmune Diabetes of Adults or LADA:
In some patients, slower destruction of pancreatic Beta ( ) cells occurs, hence, the onset is slow, often over several years. This type is called Latent Autoimmune Diabetes in Adults (LADA) since it manifests in adulthood, and onset is insidious.
These patients have positive blood tests for autoantibodies (eg. Anti- GAD antibodies). These patients may be treated with oral hypoglycemic agents initially but subsequently, require insulin.
Maturity-onset Diabetes of the Young (MODY):
About 1-2% of diabetics suffer from a rare form of diabetes labeled as MODY now named – Monogenic Diabetes in which there is a mutation of a single gene amongst the various gene defect in Type 2 diabetes. These patients have a strong family history of three generations and respond to sulphonylureas.
Fibro Calculous Pancreatic Diabetes:
Fibro Calculous Pancreatic Diabetes could occur secondary to pancreatic inflammation (pancreatitis), calcium deposition in the pancreas (calcific pancreatitis), drugs (eg steroids drugs used after transplant to prevent kidney rejection).
This diabetes is seen in India and tropics. These patients complain of abdominal pain, sticky stools and are dependent on Insulin. Toxin-induced destruction happens in both exocrine and endocrine function.
Secondary Diabetes is when there is hyperglycemia secondary to other diseases like Cushing’s, Pituitary, etc. Also, a congenital rare disease associated with Insulin resistance can lead to diabetes.