What is diabetes?
Glucose is essential for the survival of all the cells in the body. It is the main energy source for all the metabolic activities in the body. Glucose reaches body tissues through blood circulation. It is essential to maintain adequate blood glucose level so that body tissues can utilize it appropriately. Blood glucose either above or below normal levels is dangerous. Various hormones regulate blood glucose levels. Most important among them is insulin. Insulin is secreted from beta cells of islets of Langerhan’s in a gland called pancreas. Insulin is essential to maintain blood glucose within normal limits. With the help of insulin body tissues utilize glucose. Insulin acts via insulin receptors present on different cells of the body. Insulin can be compared to a key and insulin receptor to a lock. When insulin attaches to its receptor on the cell, it results in opening of the gates for glucose. Glucose enters the cells, and is utilized by the cells. When glucose level in the blood increases, insulin is produced and it brings back the glucose to normal levels.
Blood glucose should be below 100 mg/dl if an individual is fasting (FBS – Fasting blood sugar). And it should be < 140 mg/dl two hours after food intake (PPBS – Postprandial blood sugar). Diabetes mellitus is a disease in which an individual’s blood glucose levels are above normal either due to inadequate production of insulin and/ or due to reduced cell response to insulin (increased insulin resistance). Diabetes – Fasting blood sugar levels are ≥ 126 mg/dl and postprandial blood sugar levels are ≥ 200 mg/dl. Impaired Glucose Tolerance – Fasting sugar levels are between 100 and 125 mg/dl and postprandial blood sugar levels are between 140 and 199 mg/dl. Impaired Fasting Glycemia – Fasting sugar levels are between 100 and 125 mg/dl and postprandial blood sugar levels are between < 140 mg/dl. Prediabetes – Both impaired glucose tolerance and impaired fasting glucose are considered as prediabetes. What are the types of diabetes?
Diabetes mellitus is divided into 3 subgroups.
Type 1 diabetes – It occurs as a result of reduced or absent production of insulin. This is mostly due to autoimmune destruction of beta cells of pancreas (body defense senses its own cells as enemies and destroy them). In others the exact reason is not known (idiopathic). Type 1 diabetic patient should be on lifelong exogenous insulin. Usually it is diagnosed in childhood. A subgroup of type 1 diabetes that occurs in adults is called latent autoimmune diabetes of adults (LADA). In this condition destruction of beta cells and disease progression is slow. Type 2 diabetes – In this, there is increased peripheral insulin resistance. It means that number of insulin receptors are reduced (reduced insulin sensitivity) and as a result insulin action is reduced. As the disease progress there is insufficient production of insulin to compensate increased insulin resistance. There is also increased endogenous glucose production and increased secretion of a hormone called glucogan. This hormone is produced from alfa cells of islet cells of Langerhan’s and increases blood glucose levels. Most of the type 2 diabetic patients are overweight or obese. Obesity itself contributes to increased insulin resistance and inadequate insulin production.
Secondary diabetes – Diseases of pancreas like chronic pancreatitis and cystic fibrosis; certain medications like steroids, thiazide diuretics and beta agonists; and endocrine diseases also cause diabetes. These are grouped under secondary diabetes. Diabetes occurring during pregnancy is called gestational diabetes. This may progress to type 2 diabetes later.
What are the symptoms of diabetes?
Classical symptoms of increased thirst with excess drinking of water (polydypsia), increased hunger with excess eating (polyphagia), increased urination (polyuria), weight loss are present in some patients. As blood sugar is high more amount of sugar enters urine taking water along with that. This results in increased urination. Water loss results in increased thirst and more amount of water intake (polydypsia). Even though blood sugar is high body tissues cannot utilize glucose because of inadequate or absent insulin. This results in increased hunger and excess eating (polyphagia). In spite of eating more patients lose weight.
Detection of type 2 diabetes is often incidental while investigating for some other problem. Some patients will have non specific symptoms like weakness, tiredness, tingling and numbness. Most of them are obese. But type 2 diabetes can occur even in normal BMI individuals also. Some present with non healing wounds over legs, increased incidence of infections, blurring of vision and increased urination.
Diabetes can result in several complications. Macrovascular complications occur due to accumulation of fat within the walls of the blood vessels (atherosclerosis) resulting in narrowing of the blood vessels, reduced or loss of blood supply to the affected part. Coronary artery disease (Ischaemic heart disease), peripheral vascular disease (reduced or loss of blood supply to the legs resulting in non healing ulcers, gangrene of toes or limbs), stroke (reduced blood supply to brain causing damage), erectile dysfunction (reduced blood supply to penis) belong to this category. Onset of macrovascular complications correlates with the onset of insulin resistance. Fluctuations in blood glucose and increased blood glucose result in microvascular complications. Diabetic retinopathy (damage to the retina in eye and blindness), diabetic nephropathy (damage to the kidney, loss of protein in the urine, renal failure) are examples. Glucose accumulation in lens of the eye leads to cataract formation (lens becomes opaque). Diabetes affects nerves also resulting diabetic neuropathy (tingling and numbness in feet, loss of sensation) resulting in injuries followed by infection, ulcers and loss of body tissues. Loss of blood supply to the feet, loss of sensation and high blood sugar lead to diabetic foot ulcers. Presence of hypertension, hyperlipidemia, smoking, alcohol intake and anxiety increases the risk of several complications. Diabetic patients are also at risk of acute complications like hypoglycemia (reduced blood sugar), diabetic ketoacidosis (altered mental state, high blood sugar, ketone bodies in urine), nonketotic hyperosmolar coma (coma, dehydration, high blood sugar).
Urine sugar, fasting blood sugar and postprandial blood sugar are routinely done to diagnose diabetes. If there is doubt about presence of diabetes oral glucose tolerance test is done. If glucose is given by mouth its blood levels will be kept within normal limits by glucose mediated insulin response in the early phase of food intake. Hb A1C measurements indicate glycemic control in the past 3 months. There are several new tests are available to evaluate diabetes.
Studies have shown that metabolic surgery is superior to medical management in patients suffering from obesity (especially if BMI is ≥ 30 kg/m2) and type 2 diabetes. If such individual is fit, we offer metabolic surgery. Resolution of diabetes occur even in remaining asian obese type 2 diabetics (BMI ≥ 25 kg/m2 to BMI < 30 kg/m2) and even in normal BMI asian diabetics after metabolic surgery. As trials are still going on, we take detailed informed consent from the patient and ethical committee approval before performing metabolic surgery in patients with BMI < 30 kg/m2.
First line of therapy to manage diabetes in general is lifestyle changes in the form of diet modification and exercise. Patient needs to understand type 2 diabetes and its treatment aspects. Main aim of therapy is to maintain HbA1c levels below 6.5%. But in older diabetics with multiple co-morbid conditions this strict glycemic control (strictly controlling blood glucose) is not possible and not advisable. If lifestyle management doesn’t control diabetes then oral medications are added. First step is to add metformin. If patient doesn’t respond then we add GLP 1 analogs, DPP 4 inhibitors, thiazolidinedione, sulfonyl urea agents or insulin tailored to the individual patient’s requirements. Finally patient may settle with insulin alone or GLP 1 analog with insulin. We prescribe insulin on once, twice or thrice daily basis depending on individual patient’s requirement.
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