Understanding Diabetes: Types, Causes, and Early Warning Signs
Know about diabetes, types, causes, signs, symptoms, diagnosis, risk factors and treatment options.
Written by Dr. M L Ezhilarasan
Reviewed by Dr. D Bhanu Prakash MBBS, AFIH, Advanced certificate in critical care medicine, Fellowship in critical care medicine
Last updated on 16th Sep, 2025
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Introduction
Diabetes is far more than a simple problem of "high blood sugar." It's a complex metabolic disorder that affects how your body turns food into energy, with ramifications for nearly every organ system. Are you experiencing unexplained fatigue? This could be more than just passing quirks; they might be your body's distress signals. This article will demystify diabetes by exploring its different types, uncovering the root causes behind them, and connecting those causes to the symptoms you can't afford to ignore. We'll break down the science into understandable parts, helping you recognise the early warnings and understand the critical differences between Type 1, Type 2, and other forms of this condition.
The Core Problem: Insulin and Glucose Dysregulation
At its heart, all diabetes revolves around a single hormone: insulin. Understanding its role is key to understanding everything else.
The Role of the Pancreas and Insulin
Imagine your digestive system breaks down carbohydrates into glucose, a simple sugar that enters your bloodstream. Glucose is the primary fuel for your body. The pancreas, an organ behind your stomach, contains beta cells that act as the body's sophisticated fuel managers. Their job is to release insulin in response to rising blood glucose levels. Insulin acts like a key, unlocking your body's muscle, fat, and liver cells to allow glucose to enter and be used for energy. This process keeps your blood sugar levels in a healthy, narrow range.
Consult a Diabetologist for Personalised Advice
What is Insulin Resistance?
Insulin resistance is a central concept in Type 2 diabetes. It occurs when your cells stop responding efficiently to the "key" of insulin. They resist its attempt to unlock them. In response, your pancreas's beta cells pump out even more insulin to try and force the glucose into the resistant cells. This works for a while, leading to high insulin levels but normal blood sugar. It's like a security guard who has gone deaf; you have to shout louder and louder (produce more insulin) to get the same message across.
Type 1 Diabetes: The Autoimmune Response
Type 1 diabetes (T1D) is an autoimmune condition, meaning the body's own immune system mistakenly turns against itself.
What Triggers the Autoimmune Attack?
In T1D, the immune system identifies the insulin-producing beta cells in the pancreas as foreign invaders and systematically destroys them. The exact cause of type 1 diabetes is not fully understood, but it's believed to involve a combination of genetic predisposition and an environmental trigger, such as a viral infection (e.g., enteroviruses). This trigger may kick-start the autoimmune process in genetically susceptible individuals.
The Progression and Onset of Symptoms
This destruction can happen quickly or over several years. As the beta cell population declines, the pancreas produces less and less insulin. Eventually, it produces almost none. Without insulin, glucose cannot enter cells and builds up to dangerously high levels in the bloodstream (hyperglycemia). The symptoms of type 1 diabetes often appear suddenly and severely in children and young adults, as the body goes into a crisis without its essential fuel key.
Type 2 Diabetes: The Lifestyle and Genetic Link
Type 2 diabetes (T2D) is the most common form, accounting for over 90% of cases. It's characterized by a dual problem: insulin resistance and a relative insulin deficiency.
The Primary Driver: Insulin Resistance
As described earlier, insulin resistance is the hallmark of early T2D. The body's cells don't respond well to insulin, so glucose struggles to enter them. Risk factors for insulin resistance include being overweight (especially with abdominal fat), physical inactivity, and an unhealthy diet high in processed foods and sugars.
Beta-Cell Exhaustion and Decline
For years, the pancreas compensates for insulin resistance by working overtime to produce more insulin. However, eventually, the beta cells become exhausted and can't keep up with the massive demand. They begin to fail and die off. This leads to a progressive decline in insulin production, making blood sugar levels rise even further.
Key Risk Factors for Developing Type 2 Diabetes
Genetics/Family History: Having a parent or sibling with T2D significantly increases your risk.
- Weight: Excess fat, particularly visceral fat around the organs, promotes inflammation and insulin resistance.
- Physical Inactivity: Activity helps muscles use glucose and improves insulin sensitivity.
- Age: Risk increases after age 45, though it is rising rapidly in younger populations.
- Prediabetes: A condition where blood sugar is higher than normal but not yet high enough for a diabetes diagnosis.
- Gestational Diabetes: A history of diabetes during pregnancy increases a woman's future risk.
If you recognise several of these risk factors in yourself, it may be wise to consult a doctor online with Apollo24|7 for a preemptive risk assessment and guidance.
Gestational Diabetes: Diabetes During Pregnancy
Gestational diabetes develops during pregnancy in women who didn't previously have diabetes.
How Pregnancy Hormones Affect Insulin
Hormones produced by the placenta help the baby develop, but also block the action of the mother's insulin—a condition called insulin resistance. All pregnant women have some insulin resistance late in pregnancy. However, if the pancreas can't produce enough extra insulin to overcome this resistance, blood glucose levels rise, leading to gestational diabetes. It typically resolves after childbirth, but it is a major red flag for future health.
Risks for Mother and Baby
Untreated, high blood sugar can cause problems for both, including a larger baby (leading to difficult delivery), premature birth, preeclampsia in the mother, and a higher risk of the child developing obesity and type 2 diabetes later in life.
Connecting the Cause to the Signs: Why Symptoms Appear
The symptoms of diabetes are the direct physical consequences of high blood glucose levels and the body's subsequent reactions.
The Classic Triad: Polyuria, Polydipsia, Polyphagia
Polyuria (Frequent Urination): The kidneys work to filter excess sugar from your blood. When blood sugar is extremely high, they can't reabsorb all the sugar, so it spills into the urine, drawing water with it. This leads to producing large amounts of urine.
- Polydipsia (Extreme Thirst): As you lose fluid through frequent urination, you become dehydrated, triggering intense thirst.
- Polyphagia (Increased Hunger): Without insulin to shuttle glucose into cells, your muscles and organs are starved of energy. This lack of energy triggers intense hunger, even though you may be eating plenty.
Fatigue, Blurred Vision, and Slow Healing
It includes:
- Fatigue stems directly from your cells being deprived of their main energy source (glucose).
- Blurred Vision: High blood sugar can cause fluid to be pulled from the lenses of your eyes, affecting their ability to focus.
- Slow-Healing Sores: High blood sugar can impair blood flow and damage nerves, and it also creates an environment where bacteria can thrive, all of which slow the healing process.
The Critical Stage: Understanding Prediabetes
Prediabetes is a warning sign where blood sugar levels are higher than normal but not yet diagnostic of diabetes. It's caused by the early stages of insulin resistance. The crucial insight is that this stage is often reversible. Through sustained lifestyle changes—modest weight loss (5-7% of body weight) and at least 150 minutes of moderate exercise per week—you can improve insulin sensitivity and prevent or delay the progression to Type 2 diabetes.
Consult a Diabetologist for Personalised Advice
Diagnosis: How Diabetes is Confirmed
Doctors use several blood tests:
- HbA1c Test: Measures your average blood sugar level over the past 2-3 months. An A1c level of 6.5% or higher indicates diabetes.
- Fasting Plasma Glucose (FPG): Tests blood sugar after an overnight fast. A level of 126 mg/dL or higher indicates diabetes.
- Oral Glucose Tolerance Test (OGTT): Checks blood sugar before and after drinking a sugary liquid. A 2-hour level of 200 mg/dL or higher indicates diabetes.
Consult a Diabetologist for Personalised Advice
Dr. Nithin N T
General Physician
6 Years • MBBS, MD General Medicine
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr Venkata Naga Sai Tribhushan Rambhatla
General Physician
3 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Ankitha
Internal Medicine Specialist Diabetologist
6 Years • MD INTERNAL MEDICINE
Bengaluru
Apollo Medical Center, Marathahalli, Bengaluru
(25+ Patients)
Dr. Arthi S
Family Physician
3 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr Syed Mateen Pasha
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Consult a Diabetologist for Personalised Advice
Dr. Nithin N T
General Physician
6 Years • MBBS, MD General Medicine
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr Venkata Naga Sai Tribhushan Rambhatla
General Physician
3 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Ankitha
Internal Medicine Specialist Diabetologist
6 Years • MD INTERNAL MEDICINE
Bengaluru
Apollo Medical Center, Marathahalli, Bengaluru
(25+ Patients)
Dr. Arthi S
Family Physician
3 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr Syed Mateen Pasha
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
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Frequently Asked Questions
What is the main difference between Type 1 and Type 2 diabetes?
The main difference is the cause. Type 1 is an autoimmune disease where the body destroys its own insulin-producing cells, requiring lifelong insulin therapy. Type 2 is primarily linked to insulin resistance and lifestyle factors, often managed with diet, exercise, oral medication, and sometimes insulin.
Can eating too much sugar directly cause diabetes?
Not directly. However, consistently consuming high-sugar, high-calorie foods and drinks can lead to weight gain, which is a major risk factor for developing insulin resistance and Type 2 diabetes. It's a contributing factor, not a sole cause.
Is gestational diabetes permanent?
Usually not. It typically goes away after the baby is born. However, it significantly increases both the mother's and child's risk of developing Type 2 diabetes later in life, making ongoing monitoring essential.
What are the first signs of diabetes I should look out for?
The most common early signs of diabetes are unusual thirst, frequent urination (especially at night), extreme fatigue, blurred vision, and increased hunger. If you notice a cluster of these, it's wise to get checked.
Can diabetes be cured?
Currently, there is no cure for diabetes. However, Type 2 diabetes can often be put into remission through significant, sustained weight loss and lifestyle changes, meaning blood sugar levels remain normal without medication. Type 1 diabetes requires lifelong insulin treatment as there is no remission.