Pancreas has been a rare case that it is called a mixed gland, acting as both exocrine and endocrine glands. The islets of Langerhans that constitutes numerous microscopic clusters of endocrine cells scattered in pancreas secrete hormones that regulate blood glucose level. The islets of Langerhans have four functioning endocrine cells: i. Alpha cells – secrete glucagon to increase blood glucose levels by stimulating the conversion of glycogen to glucose, called glycogenolysis.ii. Beta cells – secrete insulin to reduce blood glucose levels by stimulating the uptake of glucose by cells.iii. Delta cells – secrete somatostatin which inhibit the release of insulin and glucagon. iv. Gamma cells or PP cells – secrete pancreatic polypeptideInsulin is the most significant blood glucose regulating hormone in which any imbalance will result in diabetes associated with other severe complications. Diabetes can be defined as a chronic disorder of energy metabolism resulting from an imbalance between insulin availability and insulin need. It occurs owing to either insufficient insulin produced by pancreas or inability of body cells to respond to the insulin. Doctors usually refer to diabetes as diabetes mellitus. World Health Organization(WHO) defines diabetes as a chronic, progressive noncommunicable disease(NCD) characterized by abnormally high blood glucose level called hyperglycemia and disruption of the metabolism of carbohydrates, fats and proteins. Diabetes is a main contributor to coronary heart disease, stroke, renal diseases, kidney failure, blindness and lower extremity amputations. Today, everyone is aware of the prevalence and risk factors of diabetes because the number of diabetes cases is on the rise all over the world. According to the Global Report on Diabetes 2016 presented by WHO, there were approximately 422 millions of adults worldwide being diagnosed with diabetes. This was four times more than the number of cases in 1980, namely 108 million. Further increment in diabetes is expected in developing countries like Malaysia and China because of sedentary lifestyles, unhealthy diets, obesity and population growth. Diabetes has been the leading cause of death worldwide as 1.5 millions of death was reported in 2012 due to the direct cause of diabetes while hyperglycemia contributes another 2.2 millions death. The overall death number resulting from both causes thus total up to 3.7 millions. Hyperglycemia is normally associated with high risk of cardiovascular diseases and obesity. One in ten adults with high blood glucose level are diagnosed with obesity. Nearly half of the deaths in people with hyperglycemia occurs before 70 years old. Now, the number of deaths attributed to the diabetes each year has risen to 1.6 millions. The number of diabetes cases is estimated to be doubled by the year 2025. Besides, by the year 2025, the age of onset for diabetes varies. In developing countries, adults aged 45 to 64 are at the high risk of suffering diabetes whereas in developed countries, occurrence of diabetes is estimated to be higher in adults over age 65. Diabetes occurs in woman and man at equivalent ratio but cause different effects. Globally, around 199 millions of women suffered from diabetes and two in five women with diabetes are aged 20 and older. They face a higher risk of heart disease and low survival rates than man with diabetes. Thus, more women die in diabetes. In case of geographical distribution of diabetes, its morbidity is higher in low- and middle-income countries like Africa, India and Asia. Diabetes is the global epidemic and more common in the more developed countries including USA and Singapore. One of the risk factors that can link to this is that advanced technological infrastructure and industrialization lead to high level of stress, lower demands of labour and higher tendency to sedentary lifestyle with less physical activity. As a result, people there are prone to weight gain and diabetes, especially type 2 diabetes. In 2015, Africa was reported to have 14.2 million population being diagnosed with diabetes, however has the highest percentage of undiagnosed diabetes cases. High prevalence of diabetes in Asia can be attributed to China and India which IDF reported as the countries with highest incidence of diabetes. IDF estimated that more than 60.5 millions population in North America or USA will get affected by diabetes in 2040. According to the American Diabetes Association, every 21 seconds one person in USA is diagnosed with diabetes. In short, a drastic increase in the prevalence of diabetes is expected in China, India, USA and Africa.Generally, there are three types of diabetes: (1) Type 1 diabetes called insulin-dependent or juvenile-onset diabetes occurs because the beta cells in islets of Langerhans are destroyed by the autoimmune process. This results in a lack of insulin production. In such condition, the glucagon levels rise and beta cells fail to respond to all insulin-producing stimuli. This form is immune-mediated (Type 1A) in most cases and few cases of type 1 diabetes are idiopathic form (type 1B) in which there is no evidence of autoimmunity or any unknown cause. (2) Type 2 diabetes called insulin-independent or adult-onset diabetes is more prevalent in people aged 60 and older. The main cause is inability of body cells to use the insulin effectively called insulin resistance which happens as the cells are resistant to attachment to their cellular receptors and subsequent action although the insulin level is normal but ineffective. The main risk factors of type 2 diabetes are obesity and sedentary lifestyles with less physical activity. (3) Gestational diabetes is a condition of hyperglycemia found during pregnancy. Because of metabolic changes during pregnancy or combination of insulin resistance and impaired insulin secretion, approximately 4% of all pregnancies are diagnosed with gestational diabetes, but their glucose metabolism regain normality after pregnancy. The down side is that they are more susceptible to type 2 diabetes than those without gestational diabetes.The disturbance of carbohydrate, fat and protein in diabetes over time causes serious damage to all of our body system, especially nerve and blood vessels. The complications of diabetes, along with their severity and organs involved vary in patients. Acute complications of diabetes are serious and difficult to treat. i. Diabetic ketoacidosis (DKA) is commonly seen in type 1 diabetes as the insulin deficiency results in lipolysis in the adipose tissue in which the lipase is not inhibited by insulin, so free fatty acids enter the circulating bloodstream and uptake by the liver to be oxidised by acetyl CoA to ketone bodies. The rate of this ketogenesis is even higher when glucagon levels rise and exceeds the rate at which the ketone bodies are used by muscles. Excessive ketone bodies thus can be seen in blood in ketonaemia and in urine in ketonuria. Over time, DKA happens as the ketone bodies are not removed from the body and cause metabolic acidosis. The clinical manifestations include nausea, vomiting, polyuria and coma. Treatment is with insulin and fluid replacement.ii. Hyperosmolar hyperglycaemic nonketotic coma (HHS) is common in type 2 diabetes adults with hyperglycemia(800 to 2000 mg/dl), hyperosmolarity (higher than 310mOsm/L), mild ketonuria, dehydration and absence of acidosis. We can see that there is lack of ketosis in HHS compared with DKA. When the insulin is ineffective, blood glucose level is high (hyperglycemia) and the high plasma osmolarity causes the diffusion of water out from body cells to dilute the blood glucose. The cells become dehydrated. Patients with HHS exhibit symptoms like dehydration, extreme thirst, hypotension, polydipsia, thromboembolus, polyuria, glucosuria, seizure, coma and so on. HHS can be treated with insulin, electrolyte or fluid replacement. iii. Hypoglycemia called insulin reaction is a condition of below-normal blood glucose level(70 mg/dl or less) as a result of excessive circulating insulin. It can be seen in type 1 diabetes patients who receive insulin injections in too high dose, fasting or skipped meal, or increased exercise. The onset of hypoglycemia is rapid and can produce some severe damage to the brain and nervous system. Permanent brain damage, headache, difficulty in learning, slurred speech, coma and seizure all are related to brain function as the glucose is essential energy source for brain as well. Besides, Somogyi effect may occur and induce rebound hyperglycemia because the stress hormones are secreted in response to the low blood glucose level at certain point. To treat this, intake of food should increase and the dose of insulin need to be reduced. Late or chronic complications of diabetes are also common in type 1 and 2 diabetes. The time of onset is after 15-20 years. It encompasses:a) Diabetic peripheral neuropathy is quite prevalent in patients with diabetes and its effect may extend to the somatic and autonomic nervous system. It is usually characterised by the segmental demyelination that damages the Schwann cells and axons. Consequently, the transmission of nerve impulses is slowed down. Another pathologic change is that the vessel ischemia causes the walls of the nutrient vessels that supply the nerve to be thickened. In sensory neuropathy, the somatosensory neurons carry pain impulses, resulting in diabetic peripheral neuropathic pain (DPNP). The loss of sensory function like sensation weakens the stress-bearing portion of joint, leading to neuropathic joints. All these diminished perception of vibration, pain and temperature will bring discomforts. In autonomic neuropathy, most of the internal body processes like regulation of body temperature, heartbeat and blood pressure are affected as autonomic nervous system mainly governs involuntary actions in our body. b) Diabetic nephropathy is featured with four types of lesions that take place in the kidney, namely (1) diffuse glomerulosclerosis and nodular glomerulosclerosis, (2) Armanni-Ebstein lesion, (3) diabetic pyelonephritis and necrotising renal papillitis, (4) vascular lesions like hyaline arteriolosclerosis of afferent and efferent arterioles and atheromas of renal arteries. Patients with diabetic nephropathy will experience an increase in elimination of albumin(30-300mg per day) through urine excretion, called microalbuminemia. Since diabetic nephropathy mainly affects kidney, it is reported to be the primary cause of kidney failure or known as end-stage renal disease.c) Diabetic retinopathy is common in all cases of type 1 diabetes and more than 60% of type 2 diabetes after 20 years long persistent occurrence of diabetes. As its name suggests, it is correlated to vision and may significantly cause blindness in patients with diabetes. The main determinant of diabetic retinopathy is that the microvessels of retina is occluded, retinal ischemia and tissue death. Other characteristics includes detachment of retina, neovascularization and associated hemorrhage. Therefore, in order to prevent this, patients with diabetes are advised to go for regular dilated eye examinations. Treatment includes the use of laser photocoagulation in the destruction and scarring of the proliferative lesions. d) Macrovascular complications includes coronary artery disease, myocardial infarction, stroke and cerebrovascular disease caused by atherosclerosis which is another early complication of diabetes. Reasons like obesity, hyperlipidaemia and hypertension lead to deposition of lipid plaques on the internal lining of blood vessels which become thickened and slows down the blood flow. Ischemia then occurs at affected tissue. This further increases the risk of getting gangrene of lower limb, diabetic foot ulcers and limb amputation as a result of the necrotic tissue of foot with reduced blood supply. e) Infection and diabetic foot ulcers have very high incidence in patients with diabetes. Diminished vascular perfusion to nerve tissues along with increased pressure and stress are contributors of foot ulcer. If the ulcer is unhealed, it will be worsened by infection that spreads through the bone of whole foot, so lead to amputation. In summary, the morbidity rate of diabetes, especially Type 2 diabetes is on the alarming rise. The risk factors include family history, unhealthy diet, lack of exercise and overweight. Compared to Type 1 diabetes, Type 2 diabetes is preventable and predominantly caused by unhealthy lifestyle, so a well-balanced diet and regular exercise effectively lower the risk as prevention is always better than cure. Untreated diabetes won`t heal itself, but it even put your life at risk.