Type 2 Diabetes

Type 2 diabetes (T2D), also known as adult-onset diabetes or noninsulin-dependent diabetes mellitus (NIDDM), is characterised by high blood sugar, insulin resistance, and relative insulin deficiency. It predominantly affects middle-aged and older adults but is increasingly seen in younger populations.

Signs and Symptoms

Classic symptoms include increased thirst (polydipsia), frequent urination (polyuria), increased hunger (polyphagia), and unexplained weight loss. Additional symptoms can include blurred vision, fatigue, recurrent infections, and peripheral neuropathy.

Some individuals may experience no symptoms initially and are diagnosed through routine testing.

Complications

Type 2 diabetes is a chronic condition that can lead to numerous complications, significantly shortening life expectancy by about ten years. Complications include:

• Cardiovascular disease (increased risk of heart disease and stroke)
• Diabetic retinopathy leading to blindness
• Kidney failure
• Poor blood flow in limbs leading to amputations
• Increased risk of cognitive dysfunction and dementia
• Skin conditions like acanthosis nigricans
• Diabetic ketoacidosis (uncommon in T2D but possible)
• Increased susceptibility to infections

Causes

The development of T2D is due to a combination of genetic and lifestyle factors. Major risk factors include obesity, lack of physical activity, poor diet, and psychological stress.

Genetic predisposition plays a significant role, with numerous genes contributing to the risk.

Lifestyle Factors

Lifestyle choices significantly impact the development of T2D. Factors such as obesity, sedentary behaviour, poor diet (high in sugars and unhealthy fats), and stress are very important contributors.

Excessive consumption of sugar-sweetened beverages and lack of sleep are also linked to increased risk.

Genetics

Genetic factors account for a substantial portion of the risk, with over 36 genes identified that contribute to the susceptibility. Monogenic forms of diabetes, like maturity onset diabetes of the young (MODY), account for a small percentage of cases.

Medical Conditions

Certain medical conditions and medications can predispose individuals to T2D. These include gestational diabetes, hyperthyroidism, Cushing's syndrome, and the use of glucocorticoids and atypical antipsychotics.

Pathophysiology

Type 2 diabetes results from a combination of insulin resistance and inadequate insulin secretion. Insulin resistance primarily affects muscles, liver, and fat tissue, leading to improper glucose regulation.

Over time, beta cell function deteriorates, reducing insulin secretion and exacerbating hyperglycaemia.

Diagnosis

Diagnosis involves blood tests such as fasting plasma glucose, oral glucose tolerance test, and glycated haemoglobin (A1C). The World Health Organisation defines diabetes based on elevated blood glucose levels confirmed on two occasions.

Prevention

Prevention of T2D involves maintaining a healthy weight, regular physical activity, and a balanced diet rich in fruits, vegetables, and low in sugar and saturated fats. Lifestyle modifications can reduce the risk of developing diabetes by more than half.

Management

Management focuses on lifestyle interventions, blood glucose monitoring, and controlling cardiovascular risk factors. First-line treatment typically includes metformin, followed by additional medications or insulin if necessary.

Regular exercise and dietary changes are very important. Bariatric surgery can be an option for obese patients, leading to significant improvements in blood sugar control.

Epidemiology

Type 2 diabetes has become a global epidemic, with approximately 392 million people affected worldwide as of 2015. The incidence has risen dramatically in parallel with increasing obesity rates.

Certain ethnic groups, such as South Asians, Pacific Islanders, and Native Americans, are at higher risk.

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Self-assessment MCQs (single best answer)

What is the primary characteristic of type 2 diabetes?

Which of the following is NOT a common symptom of type 2 diabetes?

Which test is commonly used to diagnose type 2 diabetes?

What lifestyle modification is most effective in preventing type 2 diabetes?

Which of the following medications is generally recommended as the first-line treatment for type 2 diabetes?

Which long-term complication is NOT commonly associated with type 2 diabetes?

What is the primary cause of insulin resistance in type 2 diabetes?

Which population is at higher risk for developing type 2 diabetes?

Which dietary factor is associated with an increased risk of developing type 2 diabetes?

Which condition is characterised by very high blood sugar and a decreased level of consciousness but is uncommon in type 2 diabetes?