Diabetes Mellitus

Overview

What is Diabetes mellitus (DM)?

Diabetes mellitus (DM), more simply called diabetes, is a serious, chronic condition that occurs when there are raised levels of glucose in a person’s blood because their body cannot produce any or enough of the hormone insulin, or cannot effectively use the insulin it produces. People living with DM are at risk of developing a number of serious and life-threatening complications, leading to an increased need for medical care, a reduced quality of life, and undue stress on families. DM and its complications, if not well managed, can lead to frequent hospital admissions and premature death. Therefore, DM is a serious global health problem.¹

The pathophysiology of DM¹

Insulin is an essential hormone produced in the pancreas. It allows glucose from the bloodstream to enter the body’s cells where that glucose is converted into energy. Insulin is also essential for the metabolism of protein and fat. A lack of insulin, or the inability of cells to respond to it, leads to high levels of blood glucose (hyperglycemia), which is the clinical indicator of DM.

Type 1 DM is caused by an autoimmune reaction in which the body’s immune system attacks the insulin-producing β cells of the pancreas. As a result, the body produces very little or no insulin. The causes of this autoimmune reaction are not fully understood but a likely explanation is that the combination of genetic susceptibility and an environmental trigger. Type 1 DM occurs most frequently in children and young people.

In type 2 DM, hyperglycemia is the result, initially, of the inability of the body’s cells to respond fully to insulin, a situation termed ‘insulin resistance’. During the state of insulin resistance, the hormone is ineffective and, in due course, prompts an increase in insulin production. Over time, inadequate production of insulin can develop as a result of failure of the pancreatic β cells to keep up with demand. Type 2 DM is most commonly seen in adults, but is increasingly seen in children and younger adults owing to rising levels of obesity, physical inactivity and inappropriate diet.

Facts about DM²

The epidemiology of DM in Taiwan from 2005 to 2014.

• Both the prevalence and incidence rates increased during the 10 years, which may be partly due to the aging and urbanized society.
• Better care in diabetes, lipid and blood pressure management may have contributed to the decrease of prevalence of macrovascular complications, such as strokes and cardiovascular diseases, and the total mortality.

Symptoms¹

Typical symptoms of type 1 DM include:

• Excessive thirst
• Frequent urination
• Sudden weight loss
• Lack of energy, fatigue
• Constant hunger
• Blurred vision
• Bedwetting

However, these symptoms may not always be present.

Patients with type 2 DM may present with similar symptoms as above, but in general, the presentation of type 2 DM is much less dramatic and they can be completely symptomless.¹

Risk factors and causes

Type 1 DM results from the autoimmune destruction of insulin-producing β cells in the pancreas, which is thought to be contributed by genetic and environmental factors acting together.³

Genetic factors³

Potential genes involved in the pathogenesis of type 1 DM include human leukocyte antigen (HLA) genes on chromosome 6, insulin gene on chromosome 11, and at least 15 other loci.³

Environmental triggers³

Most popular candidates for environmental triggers are viruses, with enteroviruses, rotavirus and rubella being the suspects.³

On the other hand, risk factors for type 2 DM are thought to be environmental and lifestyle factors, such as:⁴

• Diets poor in fiber, phytochemicals and plant food in general
• Regular consumption of sugar-sweetened beverages
• Little physical activity
• Prolonged television and monitor viewing/sedentary time
• Exposure to road traffic (noise and fine particulate matter)
• Smoking
• Short sleep duration and poor quality
• Low socioeconomic position

Incidence and prevalence

The World Health Organization (WHO) called for action on DM on World Health Day 2016, publishing the first WHO Global report on DM. As per this report, the prevalence of DM has almost quadrupled in the past 30 years, with the number of individuals with DM increasing from 108 million in 1980 to 422 million in 2014 globally.⁵ The most updated epidemiological data published by the International DM Federation (IDF) revealed that approximately 463 million people aged 20-79 years worldwide had DM in 2019; that is, the prevalence was approximately 9.3% (men: 240.1 million; women: 222.9 million). Nearly 327.4 million patients with DM were of working age (20-64 years) and 135.6 million were elderly (65-99 years).¹

In Taiwan, the increasing prevalence of DM is consistent with the global trend. A previous nationwide longitudinal study from 2000 to 2009 demonstrated a 35% increase in the standardized prevalence rate.⁵ The most recent study showed that the age-standardized prevalence for people aged 20-79 years increased from 4.57% in 2005 to 6.45% in 2014, resulting in total of 2.2 million diabetic patients in 2014. In 2014, more than half (50.3%) of patients with DM were at least 65 years of age.⁵ The overall prevalence of DM increased from 5.82% to 8.99% in women and from 6.07% to 9.65% in men from 2005 to 2014.⁵

Although the incidence of DM still increased from 0.621% in 2005 to 0.741% in 2014, the trend seems to have stabilized in recent years. During the observation period, the increase was most obvious in patients aged 20-39 years, and the incidence increased 34% in women and 14% in men.⁵