Insulin Therapy

Insulin therapy is a treatment in which insulin — a hormone that helps the body's cells absorb sugar from the blood — is given by injection or a small pump to keep blood sugar levels in a safe range.

Normally, the pancreas (the gland behind the stomach) produces insulin on its own. In some people, the pancreas makes little or no insulin, or the body cannot use it properly. Without enough insulin, sugar builds up in the blood and starves the cells of energy. Insulin therapy replaces or supplements the missing hormone, allowing sugar to enter the cells where it is needed.

Insulin therapy is prescribed when the body cannot produce enough insulin on its own, or when other treatments are not enough to keep blood sugar under control. The main situations in which doctors recommend it include:

• Type 1 diabetes — an autoimmune condition (where the body's own immune system destroys the insulin-producing cells) that makes daily insulin essential for survival.
• Type 2 diabetes — when lifestyle changes and oral medications (tablets taken by mouth) are no longer enough to control blood sugar.
• Gestational diabetes (high blood sugar that develops during pregnancy) — when diet alone is insufficient and medication that is safe for the baby is needed.
• Hyperglycaemic crisis (a dangerous rise in blood sugar) — such as diabetic ketoacidosis (DKA), where the body breaks down fat too quickly and produces harmful acids.
• Diabetes management during surgery or serious illness — when blood sugar swings become difficult to control with tablets alone.
• Secondary diabetes — high blood sugar caused by another condition, such as chronic pancreatitis (long-term inflammation of the pancreas) or certain hormonal disorders.

Insulin therapy is not suitable for everyone. Doctors generally avoid starting it, or use it with extra caution, in the following situations:

• Recurrent severe hypoglycaemia (episodes where blood sugar falls dangerously low) that the patient cannot sense or manage.
• Patients who are unable or unwilling to monitor their blood sugar regularly, as safe insulin use depends on frequent checks.
• Certain rare insulin-allergy reactions — though alternative formulations (different types of insulin preparations) are usually available.
• Situations where the underlying cause of high blood sugar can be fully corrected by other means, making long-term insulin unnecessary.

Insulin therapy is generally safe when monitored properly, but it does carry recognised risks that patients and their care team watch for closely.

• Hypoglycaemia (low blood sugar) — the most common risk; symptoms include shakiness, sweating, confusion, and, in severe cases, loss of consciousness.
• Weight gain — insulin encourages the body to store energy, which can lead to gradual weight increase over time.
• Lipohypertrophy (a build-up of fatty tissue under the skin) — caused by injecting repeatedly into the same spot, which can make insulin absorption unpredictable.
• Injection-site reactions — redness, swelling, or mild pain where the needle is inserted, usually short-lived.
• Insulin allergy — rare; can range from a local skin reaction to, very rarely, a generalised allergic response.
• Hypoglycaemia unawareness — some long-term users lose the ability to feel early warning signs of low blood sugar, increasing the risk of a severe episode.
• Oedema (fluid retention causing swelling), particularly at the start of therapy — usually mild and temporary.

Before starting insulin therapy, the doctor and diabetes care team spend time understanding the patient's daily routine, diet, and current medications. This helps them choose the right type of insulin and the right schedule. Patients are not usually asked to fast before a clinic appointment for insulin initiation, unless blood tests are ordered at the same visit.

Several tests and assessments are typically carried out before or at the time of starting insulin:

• HbA1c (glycated haemoglobin — a blood test that shows the average blood sugar level over the past two to three months).
• Fasting and post-meal blood glucose (blood sugar) measurements.
• Kidney function tests, because the kidneys help clear some diabetes medications and affect how aggressively blood sugar is managed.
• Liver function tests.
• A review of all current medications, including supplements and herbal remedies, as some interact with insulin.
• Blood pressure and weight measurements.
• A check of the injection sites — usually the abdomen (tummy), thighs, or upper arms — to spot any existing skin changes.

The process of starting insulin therapy typically unfolds in several stages. The exact steps and their order vary depending on the hospital and whether therapy is started in a clinic or during a hospital stay:

• The doctor reviews all test results and decides on the type of insulin (for example, long-acting insulin given once or twice a day, or rapid-acting insulin given around meals).
• A diabetes nurse or educator demonstrates how to use the insulin pen or syringe, including how to draw the correct amount, choose and rotate injection sites, and dispose of needles safely.
• The patient practises the injection technique under supervision until they feel confident.
• The first dose is given, and blood sugar is checked shortly after to observe the initial response.
• Blood sugar monitoring is set up: the patient is shown how to use a glucometer (a small device that measures blood sugar from a fingertip drop of blood) and how often to check.
• A personalised plan is made covering what to do if blood sugar drops too low (hypoglycaemia) or rises too high (hyperglycaemia), including when to seek urgent help.
• Follow-up appointments are scheduled so the doctor can adjust the dose as needed.

Patients who smoke are usually advised by their care team to consider stopping, as smoking affects blood circulation and the way insulin is absorbed under the skin. Alcohol is not banned outright, but the care team typically explains how it can mask the symptoms of low blood sugar and discusses safe limits. No specific fasting is required for routine insulin injections themselves, though meal timing matters and the team will explain this in detail.

Insulin therapy is an ongoing treatment, not a one-time procedure, so aftercare is really about building safe and consistent daily habits. The goal is to keep blood sugar within the target range set by the doctor, while recognising and responding to problems quickly. Most people manage insulin therapy at home, with regular clinic visits for monitoring and dose adjustments.

• Blood sugar monitoring: check blood sugar as often as the care team recommends — this is the most important part of safe insulin use. Results guide any needed changes to doses or meal timing.
• Injection site rotation: always vary the spot where insulin is injected. Repeatedly using the same area causes lipohypertrophy (fatty lumps under the skin) that make insulin absorption uneven.
• Recognising and treating hypoglycaemia (low blood sugar): keep a fast-acting sugar source — such as glucose tablets or a sweet drink — accessible at all times. Know the warning signs: shakiness, sweating, dizziness, rapid heartbeat, or confusion.
• Storage of insulin: unused insulin is usually kept in the refrigerator; the pen or vial in current use can typically be stored at room temperature for a limited time. The care team will explain the specific storage rules for the type prescribed.
• Needle and sharps disposal: used needles must be disposed of in a puncture-resistant sharps container, never in ordinary household waste.
• Diet and meal timing: work with a dietitian (a nutrition specialist) to align meals with the insulin schedule. Skipping meals when on certain insulin types can trigger hypoglycaemia.
• Physical activity: exercise affects how quickly insulin works and how much blood sugar drops. The care team will advise on checking blood sugar before, during, and after activity.
• Sick-day rules: illness, fever, and infections can change blood sugar unpredictably. The care team will provide specific guidance on adjusting insulin and monitoring more frequently when unwell.
• Follow-up appointments: regular visits — usually every few months — allow the doctor to review HbA1c results, check injection sites, assess kidney and liver function, and adjust the insulin regimen if needed.
• Medical identification: wearing or carrying identification that states the person uses insulin is advisable, so that emergency responders can act quickly if hypoglycaemia causes unconsciousness.