Introduction

Diabetes Mellitus (DM) is a disorder that causes the blood sugar level of an individual to be abnormally high. This condition is a metabolic disease characterized by the body’s inability to produce enough insulin to regulate blood sugar. Diabetes can be early onset (type 1 diabetes) or late onset (type 2 diabetes). DM can affect the entire body and requires daily self-care such that if complications develop, it could significantly impact the quality of life and reduce life expectancy. Although there is no cure for diabetes, one can live an enjoyable life by learning about the condition and effectively managing it. 

Diabetes caused an estimated 1.5 million deaths in 2012 while complications resulting from higher-than-optimal blood glucose (including cardiovascular diseases) caused an additional 2.2 million deaths (of which an estimated 1.6 million occurred before age 70). Nigeria is one of the countries in Sub-Saharan Africa (SSA) that is currently experiencing a rising prevalence of diabetes mellitus.

Economic Burden of DM

Diabetes imposes a large economic burden on the global health-care system and the economy. This burden can be measured through direct medical costs, indirect costs associated with productivity loss, premature mortality and the negative impact of diabetes on nations’ gross domestic product (GDP).

Based on cost estimates from a recent systematic review, it has been estimated that the direct annual cost of diabetes to the world is more than US$ 827 billion (Seuring et al., 2018). The International Diabetes Federation (IDF) estimated that the total global health-care spending on diabetes more than tripled over the period of 2003 to 2013. In 2019, there were an estimated 463 million DM cases globally, and this value is expected to increase to 578 million by 2030 (IDF, 2019). Additionally, approximately 16 million adults are living with DM in Africa, with a prevalence of 3.1% (Kibirige et al., 2019).

Image 1: infographic on overview of diabetes worldwide (WHO, 2014)

Types of Diabetes

Type 1 diabetes 

It is also called insulin-dependent diabetes, juvenile diabetes or early-onset diabetes. It is an auto-immune condition in which the immune system is activated to destroy the cells that produce insulin in the pancreas. Type 1 diabetes is usually more serious as insulin is needed to control it. There is no cure and it cannot be prevented as it is not linked to modifiable lifestyle factors. About 10% of all cases worldwide are type 1 diabetes. Its onset is usually sudden and symptoms may include excessive thirst and urination, unexplained weight loss, weakness or fatigue and blurred vision.

Type 2 diabetes 

This is the most common type of diabetes which occurs after age 35. Here, it’s either the body does not produce enough insulin for proper function or the cells in the body are not responsive to insulin (insulin resistance). It is also called non-insulin dependent diabetes or adult onset diabetes. However, a growing number of younger people are now developing type 2 diabetes because of lifestyle changes such as overweight and sedentary lifestyles.

Gestational diabetes (Diabetes in pregnancy) 

A pregnant woman’s insulin needs are two to three times that of a non-pregnant woman, and in some cases, the woman’s body cannot produce enough to transport all of the glucose into the cells, resulting in a progressive rise in glucose levels. Pregnancy causes certain types of hormones (that are made by the placenta) to be released. These hormones make it harder for insulin to do its job because the growth demands of the fetus (developing baby) increases the mother’s need for insulin. Unlike type 1 and type 2 diabetes, gestational diabetes is only temporary and usually disappears after pregnancy. However, a woman who has had gestational diabetes has an increased risk (50-60%) of developing type 2 diabetes in the future (WHO, 1999).

Other types of diabetes include gastrointestinal diabetes and diabetes insipidus (due to a tumor in the posterior pituitary gland although there is no glycosuria i.e. excess sugar in the urine).

Image 2: infographic on type 2 diabetes (Source: WHO, 2014)

Figure 1: Prevalence of diabetes by country (Source: Worldbank, 2018)

Relevant statistics on diabetes

In 2013, it was estimated that over 382 million people throughout the world had diabetes (Williams textbook of endocrinology, 2013). Type 2 diabetes is increasing in prevalence worldwide with approximately 285 million people reported to have the condition in 2010, making it one of the most common non-communicable diseases globally. The number of people with diabetes rose from 108 million in 1980 to 422 million in 2014 (WHO, 2014). Prevalence has been rising more rapidly in low and middle-income countries than in high-income countries (see figure 2 and 3 below). Between 2000 and 2016, there was a 5% increase in premature mortality from diabetes. In 2019, an estimated 1.5 million deaths were directly caused by diabetes. Another 2.2 million deaths were attributable to high blood glucose in 2012 (IDF, 2019). According to a WorldBank estimate, prevalence of DM in Nigeria ranked low among other countries worldwide although a lot of data still remains under-reported (see figure 1 above). According to the International Diabetes federation, 1 in 5 people older than 65 years have diabetes while 4 out of every 5 adults with undiagnosed diabetes live in middle and low income countries (See figure 2 and 3 below).

Figure 2: prevalence of diabetes worldwide by age group and income levels (Source: IDF, 2019)

Figure 3: prevalence of undiagnosed diabetes cases based on regions (source: IDF, 2019)

Figure 4: deaths attributable to diabetes by age (IDF, 2019)

From figure 4 above, it can be observed that although diabetes affects people of all ages, the higher prevalence occurs as the age group increases. A recent meta-analysis reported that about 6 million adult Nigerians are living with DM. By geopolitical zones, the South-South zone reported the highest prevalence of diabetes (approximately 9%) compared to the North-West zone which recorded the lowest prevalence (below 3%) (Uloko et.al., 2018). This figure has been likened to a tip of an iceberg as it is estimated that two-thirds of diabetes cases in Nigeria are yet undiagnosed (IDF, 2017). This scenario which applies to most low- and middle-income countries of SSA has not only resulted in an increase in the burden of diabetes complications and deaths, but has also put a significant strain on the already weak health systems in this sub-region.

Image 3: infographic on prevalence of adult population living with diabetes in Nigeria (source: NCBI, 2018)

The increase in the prevalence of diabetes among young adults, along with increased mortality and morbidity is likely to lead to an escalation of healthcare costs and loss of economic growth. In Nigeria, this is further exacerbated by the rising poverty levels with over 83 million Nigerians reported to live in poverty by the NBS in 2020. An estimated 1 out of every 17 adults in Nigeria is living with diabetes according to the National Center for Biotechnology Information (NCBI, 2018). The number of people with diabetes is expected to reach 438 million by 2030 which represents a 54% increase from the estimates of 2010.

Figure 5: prevalence of diabetes mellitus by geopolitical zones in Nigeria (Uloko et al., 2018)

Epidemiology of Diabetes Mellitus

Genetics plays a vital role in determining who is likely to develop type 1 diabetes. Research shows that the immune system (which normally fights harmful bacteria or viruses) attacks and destroys insulin-producing cells in the pancreas leaving one with little or no insulin thus allowing sugar to build up in the bloodstream rather than into the cells. Apart from genetic factors, environmental factors also play a role in causing type 1 diabetes (Ronald et al., 2010).

For type 2 diabetes, the cells become resistant to the action of insulin and the pancreas is not able to produce enough insulin to overcome this resistance. Blood glucose builds up in the bloodstream rather than being moved into the cells where they are required for energy. Being overweight and living a sedentary lifestyle has been linked to the development of type 2 diabetes although there are also genetic and environmental factors involved.

Figure 6: Risk factors for developing type 2 diabetes (Uloko et al., 2018)

Some of the risk factors associated with type 2 diabetes (see figure 6 above) include increasing age, obesity (central obesity), dietary excesses, increased intake of animal fats, carbonated drinks, positive family history, a sedentary lifestyle, history of gestational diabetes for women, presence of hypertension, severe mental illness etc. Many of these risk factors are associated with a westernized lifestyle and increased urbanization. In particular, obesity accounts for 80-85% of all type 2 diabetes. Epidemiological studies have suggested that early life events such as low birth weight and fetal malnutrition may also be associated with increased risk of diabetes and cardiovascular disease later in life (IDF, 2007 & 2010).

Image 4: main symptoms of diabetes (source: IDF, 2019)

Diabetes and pre-diabetes are diagnosed with a fasting plasma glucose test, oral glucose tolerance test, or random plasma glucose test. Another way of testing is to use special paper strips that change color when dipped in the urine. Urine test for specific gravity, history of big babies, still births or repeated abortion can also be used in diagnosis.

Complications of DM

Complications of type 1 diabetes mellitus: These include anxiety, auditory damage, visual impairment, severe headaches, seizures, slurred speech, finger and toe damage, heart disease, rapid heartbeat and pale skin.

Type 2 Complications: Over the years, complications can develop and they relate to how blood glucose levels can affect blood vessels causing microvascular and macrovascular complications such as eye kidney and nerve damages. They are discussed in more detail below:

1, Cardiovascular disease: Affects the heart and blood vessels and may cause stroke and coronary artery disease (leading to heart attack). Cardiovascular disease is the most common cause of death in people with diabetes.

2, Kidney disease (diabetic nephropathy): Caused by damage to small blood vessels in the kidneys leading to the kidneys becoming less efficient or to fail altogether. Kidney disease is much more common in people with diabetes than in those without diabetes (USRDS, 2014).

3, Nerve disease (diabetic neuropathy): Diabetes can cause damage to the nerves throughout the body when blood glucose and blood pressure are too high. This can lead to problems with digestion, erectile dysfunction, and many other functions. Among the most commonly affected areas are the extremities, in particular the feet. Nerve damage in these areas is called peripheral neuropathy, and can lead to pain, tingling, and loss of feeling. Loss of feeling is particularly important because it can allow injuries to go unnoticed, leading to serious infections and possible amputations.

4, Eye disease (diabetic retinopathy): most people with diabetes will develop some form of eye disease (retinopathy) causing reduced vision or blindness. Consistently high levels of blood glucose, together with high blood pressure and high cholesterol, are the main causes of retinopathy. It can be managed through regular eye checks and keeping glucose and lipid levels at or close to normal. (Bourne et al., 2013)

Complications of gestational diabetes: Untreated or uncontrolled blood sugar levels can result in complications because glucose can cross the placenta thereby triggering the baby’s pancreas to produce more insulin. This can cause the baby to grow too large (macrosomia) thereby requiring a C-section birth. Preeclampsia and death can also occur.

Prevention and control

1, Weight management, especially body fat, particularly if stored around the abdomen, can increase the body’s resistance to the hormone insulin thus leading to type 2 diabetes.

2, Regular exercise helps to manage weight, improve blood circulation and pressure, reduce cholesterol and reduce blood glucose levels.

3, Eating a balanced, healthy diet helps to reduce the amount of fat in our diet, especially saturated and trans fats. Particularly, it is essential to eat more fruit, vegetables and high-fiber foods while avoiding salt intake.

4, Limit takeaway and processed foods. ‘Convenience meals’ are usually high in salt, fat and kilojoules. It’s best to cook for yourself using fresh ingredients whenever possible.

5, Too much alcohol can lead to weight gain and may increase your blood pressure and triglyceride levels. Two and one standard drinks a day is recommended for men and women respectively.

6, Quit smoking. Smokers are twice as likely to develop diabetes as non-smokers.

7, Control your blood pressure. Most people can do this with regular exercise, a balanced diet and by keeping a healthy weight. In some cases, you might need medication prescribed by your doctor.

8, Reduce your risk of cardiovascular disease. Diabetes and cardiovascular disease have many risk factors in common, including obesity and physical inactivity.

Conclusions and recommendations

The explosive increase in the prevalence of diabetes in recent years has been in the form of type 2 diabetes mellitus. There is strong epidemiological evidence that this epidemic is related to the changing lifestyle; refined foods have replaced natural whole grain, high fiber diets; and there is a lack of physical exercise partly due to sedentary lifestyles. Persons with impaired glucose tolerance and prediabetes can reduce risk of progressing to frank diabetes with proper diet and lifestyle modifications while oral hypoglycaemic drugs can be administered if diet management has failed. Innovative therapies for diabetes mellitus currently exist  which could be employed to arrest the rising prevalence of the disease. These include gene therapy, immunotherapy, artificial pancreas placement, stem cell therapy and transplantation. 

Other recommendations include;

1, Non-communicable diseases, particularly diabetes, should be given more attention in Nigeria with all health agencies given the mandate to collate data which will be needed for proper planning for control of diabetic mellitus

2, It is no longer news that the epidemiological pattern of diabetes mellitus is gradually changing with a large percentage of young adults suffering from this condition. Hence, there is the utmost need for due sensitization by public health agencies and private organizations involved in health to champion this cause.

3, Health education on diabetes, causes, symptoms, risk factors and how to monitor blood sugar levels. Also, advice on proper diet and marriage counseling to avoid marriages between diabetic families.

4, To address the “iceberg” phenomenon where lots of diabetic cases are under-reported, blood sugar testing and massive screening can be organized as part of public health strategies by both public and private organization so as to know the true extent of this disease in Nigeria.

5, One of the challenges we face as a nation in Nigeria is the lack of empirical data to draw evidence based conclusions. Although, eHealth4everyone are already collaborating with the Federal Ministry of Health (FMoH), other organizations can join in to carry out an extensive meta analysis and data collection for not only diabetes but other non communicable diseases.

References 

Uloko, A.E, Musa, B.M, Ramalan, M.A, Gezawa, I.D, Puepet, F.H, 2018. Prevalence and risk factors for diabetes mellitus in Nigeria: a systematic review and meta-analysis. Diabetes Ther. 9(3):1307–16.

International Diabetes Federation. Diabetes atlas 8th Edition. International Diabetes Federation 2017. http://www.diabetesatlas.org. Accessed 8 august 2021.

Kibirige, D., Lumu, W., Jones, A.G. et al., 2019. Understanding the manifestation of diabetes in sub Saharan Africa to inform therapeutic approaches and preventive strategies: a narrative review. Clin Diabetes Endocrinol 5; 2.  https://doi.org/10.1186/s40842-019-0077-8 

Ronald, C.W. Ma & Peter, C.Y. Tong, 2010. Epidemiology of type 2 diabetes: Textbook of Diabetes, 4th edition. Edited by R. Holt, C. Cockram, A. Flyvbjerg and B. Goldstein. © 2010 Blackwell Publishing

Oghenekaro Godwin, Egbi Sulaiman, Dazumi Ahmed, 2014. Prevalence of Diabetes Mellitus in a Rural, Agrarian Community in South-South Nigeria

Sarwar N, Gao P, Seshasai SR, Gobin R, Kaptoge S, Di Angelantonio et al., 2010. Lancet 26;375:2215-2222. Diabetes mellitus, fasting blood glucose concentration, and risk of vascular disease: a collaborative meta-analysis of 102 prospective studies. Emerging Risk Factors Collaboration.

Bourne R.R, Stevens G.A, White R.A, Smith J.L, Flaxman S.R, Price H et al., 2013. Lancet Global Health 2013;1:e339-e349 Causes of vision loss worldwide, 1990-2010: a systematic analysis.

United States Renal Data System, 2014. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 188–210. 2014 USRDS annual data report: Epidemiology of kidney disease in the United States.

International Diabetes Federation, 2007. Diabetes Atlas. (3rd edn), IDF, Brussels.

International Diabetes Federation, 2010. Diabetes Atlas. (4th edn), IDF, Brussels, Belgium. 

Akinkugbe O.O, 1997. Non-Communicable Diseases in Nigeria: National Survey (Final Report) on Hypertension, Coronary Heart Disease, Diabetes Mellitus, Haemoglobinopathies, G6PD Deficiency and Anaemia. National Expert Committee on Non- Communicable Diseases. Federal Ministry of Health and Social Services, Lagos

Definition, Diagnosis and Classification of Diabetes Mellitus and its Complications. Part 1: Diagnosis and Classification of Diabetes Mellitus (WHO/NCD/NCS/99.2). Geneva: World Health Organization; 1999.

Seuring T, Archangelidi O, Suhrcke M, 2015. The economic costs of type 2 diabetes: A global systematic review. PharmacoEconomics. 33(8): 811–31.

International Diabetes Foundation, 2019.