Diabetes mellitus -101

Updated: Jan 27

By Niranjana S. Rajalakshmi, MVSc (Vet. Microbiology)

Science Writer (Freelance)


Diabetes mellitus (mellitus means ‘honey’ in Latin), commonly called diabetes affects how your body converts food to energy. Diabetes has become a very common issue all over the world. The World Health Organisation (WHO) estimates that about 422 million people are affected by diabetes worldwide, with a greater number of affected individuals belonging to low- and middle-income countries.

What is Diabetes?

During food digestion, carbohydrates break down into glucose which is carried by the bloodstream to various organs of the body, so that all the cells receive glucose for energy. When the blood glucose level rises (for example, after a meal), the pancreas secretes a hormone called ‘insulin’ that signals the cells to take up glucose from the blood. During diabetes, there are issues with the insulin, leading to high levels of sugar in the blood. There are three main types of diabetes – type 1, type 2 and gestational diabetes.

Type 1 or insulin-dependent diabetes (previously known as Juvenile diabetes)

Type 1 diabetes can occur at any age, but it is usually diagnosed in children and young adults. It it is less common than Type 2 diabetes. In the case of type 1 diabetes, the immune cells in the body, more specifically the white blood cells mistake the pancreatic insulin-producing cells for foreign agents and destroy them leaving the body with little or no insulin. The exact cause of why this auto-immune reaction happens is still unknown.

Without insulin, glucose cannot get into the cells. So they are starved for the calories they should be receiving. Glucose builds up in the blood causing ‘hyperglycemia’. If hyperglycemia is left untreated, glucose is not available to the cells of the body. As a result, the body breaks down fat and protein stores as an alternative source of energy. As a secondary effect, during the fat breakdown, certain by-products called ‘ketones’ accumulate leading to a life-threatening condition ‘diabetic ketoacidosis’. There are no cure or prevention strategies for type 1 diabetes. However, it can be managed to a certain extent.

For treating type 1 diabetes, the goal is to keep the blood glucose within the normal range. This is done by a combination of

Insulin therapy

Routine blood glucose monitoring

Healthy diet


Type 2 diabetes

More than 1 in every 10 adults have type 2 diabetes. Unlike Type 1, the underlying mechanism of Type 2 diabetes is better understood. In Type 2 diabetes, insulin is secreted by the pancreas, but the body doesn’t respond to it. This occurs because the body cells start showing resistance to insulin – a condition called ‘insulin resistance’. This in turn causes the building up of glucose in the blood. In this stage, the pancreas can detect high levels of blood glucose and hence starts secreting more and more insulin. However, the insulin resistance worsens over time and the pancreas that keeps secreting insulin gets exhausted at a particular point. And by now, the blood glucose level would have skyrocketed!

If diabetes is left untreated, serious complications with the kidney and vision can develop.

Symptoms most often associated with diabetes mellitus:

Increased thirst and hunger

Increased urination

Weight loss (you might lose calories from frequent peeing too!)

Blurry vision

Sores that don’t heal

Tingling hands and feet

What causes insulin resistance?

Various factors contribute to this such as genetics, ethnicity, sedentary lifestyle and obesity. Of all these, obesity is considered as the most common predisposing factor for developing insulin resistance.

Diabetics people with high blood glucose levels sometimes also tend to have a sharp low in their blood glucose levels which is called ‘hypoglycemia’. This is common among people who take a high dose of insulin or other oral diabetic medications. Other causes include skipping a meal, exercising more than you normally do, which utilizes more glucose. Maintaining the balance between insulin, food, and activity isn't always easy, but your physician can work with you to try to prevent low blood sugar levels.

Gestational diabetes

Gestational diabetes is a commonly occurring complication during pregnancy and there is certainly a need for understanding what is happening in the body during gestational diabetes.

During pregnancy, a temporary organ called ‘placenta’ develops to connect the mother and the fetus. The placenta supplies the fetus with nutrients, oxygen and produces several hormones as well, to maintain pregnancy. Some of these hormones impair the activity of insulin making it less effective. This insulin counteracting effect usually begins around 24 to 28 weeks of pregnancy and the effect intensifies as the placenta grows larger and becomes most prominent in the last couple of months.

Usually, the pancreas is able to adjust by producing more insulin. But in some cases, the amount of placental hormones could be too overwhelming for the pancreas to compensate and this results in gestational diabetes. While gestational diabetes usually resolves on its own after delivery, complications may arise when the condition is very severe or poorly managed.

What are its complications?

Because of the constant high glucose level in the mother’s blood, the fetus may receive more nutrients than the required level and may grow too large. This could complicate the birth process and a C-section may be required

High levels of glucose may also stimulate the fetus to produce more insulin than usual. Shortly after delivery, the baby continues to have high insulin levels, but no longer receives glucose from the mother. So, the baby’s blood sugar levels could drop suddenly and could even lead to seizures.

Women with gestational diabetes are highly prone to developing type 2 diabetes (diabetes mellitus) especially three to six years after delivery

Hence, routine monitoring of blood sugar levels during pregnancy is required to manage gestational diabetes effectively. Once diagnosed early, it is treatable with oral diabetic medications or insulin.

Diagnosis of Diabetes

Apart from measuring the blood glucose levels, an ‘HbA1c test’ can be done which tells your average level of blood sugar over the past 2 to 3 months. The term ‘HbA1c’ refers to glycated hemoglobin. When hemoglobin, a protein within red blood cells that carries oxygen throughout your body, joins with glucose in the blood, it becomes ‘glycated’.

Red blood cells in the human body survive for 8-12 weeks after which they get renewed. Thus, measuring HbA1c reflects average blood glucose levels over that duration, providing a useful longer-term gauge of blood glucose control. Gestational diabetes is generally diagnosed by oral glucose tolerance test (OGTT) in which glucose is given and blood samples taken afterward to determine how quickly it is cleared from the blood.

Management and Prevention

Type 1 diabetes is an autoimmune condition. You can’t reverse it, you can only manage it.Diet and exercise are the foundation of diabetes management. However, Type 2 diabetes can be reversed with effective intervention and lifestyle changes.

Note: Please consult a medical professional or a trained nutritionist regarding specifics of your health and symptoms or before changing your diet or trying something new.

Disclaimer: Miyara Health does not undertake any financial/ reputational/ legal/ health related/misrepresentational impact or other obligations/ liabilities that may arise from the content.

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