Diabetes Mellitus vs Diabetes Insipidus: Understanding the Differences

Diabetes mellitus and diabetes insipidus are clinical entities that have been well described for years, but only recently have their pathophysiologic nature and long-term management been defined. Until a century ago, little was known about the course of these diseases or their underlying mechanisms. The present review will discuss a pathophysiologic model of these diseases, focusing on current concepts that are used to understand the treatment of patients and the progression of disease in affected individuals. 

Although they share the same first name and some of the symptoms, diabetes insipidus and diabetes mellitus are completely different diseases. They cause different problems and they have different treatments. In this topic, we will explain a bit about both of the diseases and then move on to what the primary differences between them are.

Diabetes mellitus is general diabetes that most of the population suffer from. It involves several conditions on how your body turns food into energy. When you eat carbohydrates, your body turns the food into a sugar called glucose and the hormone insulin regulates the flow of glucose in your bloodstream. If there is a low level of insulin secretion in your body, then your blood glucose levels will increase which leads to a condition called high blood sugar. It can cause serious health problems and if not controlled can be life-threatening. It comes in different forms

Prediabetes: It is a condition when your blood glucose levels are higher than usual but not so high that it can be diagnosed as diabetes

Type I Diabetes: This is also called insulin-dependent diabetes and is an auto-immune condition where your body attacks your pancreas with antibodies. Thus the pancreas is damaged which results in low levels of insulin secretion and high levels of blood glucose. This condition can damage the blood vessels of eyes and kidneys. The treatment involves injecting insulin into the fatty tissue under the skin with the help of syringes and insulin pens.

Type II Diabetes: It is also referred to as non-insulin-dependent diabetes. It is observed mostly in people suffering from obesity. In this condition, the patient’s body produces insulin but it is not enough to control blood glucose levels. It causes the same health complications as type 1 diabetes. The only way to keep this type of diabetes in control is to lead a healthy life; eating right, exercising and keeping a healthy weight.

Gestational Diabetes: Pregnancy can cause insulin resistance. If this leads to diabetes then doctor’s call it gestational diabetes. It is usually spotted in middle or late pregnancy. Gestational diabetes should be controlled as it poses a risk for the fetus. The new-born baby might gain weight after birth and face trouble breathing. The treatment includes meal planning for the mother, daily exercise, taking insulin and keeping weight under control.

Characteristics of Diabetes Mellitus 

Diabetes mellitus (DM) is a disease characterized by hyperglycemia that results from defects in insulin secretion or insulin action. In particular, the body's inability to respond normally to insulin has been viewed as being fundamental in the pathogenesis of DM. 

DM is commonly characterized by hyperglycemia, with an average fasting plasma glucose level between 7.8 and 11.1 mmol/L and a 2-h glucose level greater than 11.1 mmol/L; however, asymptomatic hyperglycemia, mild hyperglycemia, and mild hyperglycemia associated with impaired fasting glucose have also been observed. These abnormal glucose values are often accompanied by high insulin secretion and resistance in peripheral tissues, and severe cases are associated with small amounts of insulin secretion and resistance in the liver.

More recently, hyperglycemia has been associated with an increase in the natural killer cell activity as assessed by binding to insulin-IgG complexes. This finding has been noted in the groups with DM, and in those who have had a successful induction of remission from DM; the findings have been attributed to an increased number of circulating insulin-IgG complexes. Insulin is normally secreted into the extracellular compartment by pancreatic ß-cells in response to a glucose challenge. When there is insulin resistance, this glucose-sensing mechanism is compromised and hyperglycemia occurs despite normal insulin secretion and activity. In these individuals, insulin resistance and hyperglycemia are a result of an inability to appropriately regulate glucose homeostasis in peripheral tissues. Hyperglycemia may also result from postprandial hyperinsulinemia (especially when there is a delay in carbohydrate absorption), although this represents a relatively uncommon form of diabetes. 

Insulinomas most patients with insulinomas present with acute pancreatitis. However, a significant proportion of these patients have no objective findings on physical examination and are diagnosed by the patient's physician from indirect signs (weight loss and vague complaints). About 1% of patients have no objective laboratory findings and are diagnosed by direct history and/or physical examination. 

The majority of these patients are male. Presenting signs can be acute pancreatitis, diabetes, acromegaly, and other disorders of growth. The most common presenting sign is recurrent hypoglycemia (or diabetic ketoacidosis), which often occurs in patients with large hypersecreting islet cells and few remaining normal-functioning beta cells. Unconsciousness and death may occur without warning if no treatment is given. Fortunately, the prognosis for this condition is excellent if intervention is instituted promptly.

Diabetes Insipidus

Diabetes insipidus is a condition where your kidney produces abnormally large volumes of dilute and odourless urine. The kidneys of an affected patient can pass up to 20 litres of urine. As a result, the patient would have to drink large amounts of fluid. There are four types of diabetes insipidus:

Central: The reason behind central diabetes insipidus is damage to a person’s hypothalamus or the pituitary gland which results in abnormal production, storage and release of vasopressin. The issue causes the kidneys to remove excess fluid from the body.

Nephrogenic: The causes of this type of diabetes insipidus are gene mutation or inherited gene changes which lead to the kidneys not functioning normally. Some of the symptoms are low potassium and high calcium levels in the blood.

Dipsogenic: A defect in the thirst mechanism located in the brain's hypothalamus causes this type of diabetes insipidus which increases the thirst and the liquid intake of a person. It also suppresses vasopressin and increases the passing of urine.

Gestational: This happens during pregnancy.

The general symptoms of diabetes insipidus are:

• Thirst

• Nausea

• Dry skin

• Fatigue

• Dizziness etc.

The treatments for diabetes mellitus include hormonal therapy, medication to balance mineral levels in the body and living a healthy life.

Differences Between Diabetes Mellitus and Insipidus

Each disease has its own set of specific characteristics. The following table lists those differences.

Diabetes Insipidus vs Diabetes Mellitus