How Does Type 2 Diabetes Start? Understanding Insulin Resistance and Prediabetes

Overview

• Type 2 diabetes often develops gradually, with insulin resistance and other changes in how the body handles insulin and glucose occurring before blood sugar reaches the diabetes range.

• Your pancreas covers for this by making extra insulin. For years, this can keep sugar reports looking normal.

• Prediabetes is the stage where sugar is above normal but not yet in the diabetes range. It usually causes no symptoms.

• A simple blood test shows where you stand. Lifestyle changes can slow or even stop the slide into diabetes.

• The ICMR-INDIAB study estimated that 136 million adults in India had prediabetes in 2021.

 

Quick Answer: How Does Type 2 Diabetes Start?

Type 2 diabetes usually develops gradually, often involving insulin resistance, when the body’s cells stop responding well to insulin. To compensate, the pancreas may make more insulin. Over time, if the pancreas cannot keep up, blood sugar levels can begin to rise.

A common pattern is:

Insulin resistance → more insulin production → rising blood sugar → prediabetes → type 2 diabetes

This is not the same for everyone. Genes, lifestyle, and other health factors can affect how type 2 diabetes develops. Prediabetes may occur before type 2 diabetes, but not everyone will have a diagnosed prediabetes stage. The important point is that high blood sugar is not necessarily the first change.

What Is Type 2 Diabetes?

Type 2 diabetes is a long-term condition in which the body cannot use insulin properly and, over time, may not make enough of it. Glucose (sugar) then stays in the blood instead of moving into the cells for energy. It is the most common type of diabetes and usually develops slowly, though it can affect younger people too.

How Does Insulin Lower Blood Sugar?

When you eat, your body breaks carbohydrates down into glucose, which enters your blood. Your pancreas senses this and releases insulin.

Think of insulin as a key. It unlocks your muscle, fat and liver cells so glucose can move in and be used or stored. It also tells the liver to release less glucose. Together, these actions bring your blood sugar back down after a meal.

Insulin sensitivity describes how well your cells respond to this key. When sensitivity is good, a small amount of insulin does the job. When it drops, the same amount works less well. That is insulin resistance.

How Does Type 2 Diabetes Start?

Type 2 diabetes often develops when insulin resistance and other metabolic changes progress and the pancreas can no longer produce enough insulin to keep blood sugar in the normal range. Blood sugar may then rise into the prediabetes range and, later, the diabetes range.

Stage	What is happening in the body	What a sugar report may show
Insulin resistance	Cells respond less well to insulin	Often normal
Extra insulin	The pancreas works harder to keep sugar in range	Often normal (insulin may be high if tested)
Prediabetes	The pancreas can’t fully keep up	Above normal, below the diabetes range
Type 2 diabetes	Sugar stays in the diabetes range	Diabetes-range results

This is a general pattern. The speed varies from person to person, and not everyone with insulin resistance develops diabetes. It also explains why a normal sugar report doesn’t always tell the full story. Your body may already be working overtime.

What Causes Insulin Resistance?

Why does diabetes happen to some people and not others? There is rarely one reason. Insulin resistance can result from a mix of genetic, metabolic, and lifestyle factors:

• Extra body fat, especially around the waist
• Low physical activity
• A family history of type 2 diabetes
• Growing age
• Polycystic ovary syndrome (PCOS)
• Poor sleep or untreated sleep apnoea
• Diabetes during a past pregnancy
• Certain medicines, such as long-term steroids

Sugar alone isn’t the villain. Eating sweets doesn’t directly cause diabetes. But regularly taking in more calories than your body needs can contribute to weight gain, and extra weight around the belly is a major driver of insulin resistance.

Why Are Indians at Higher Risk?

The ICMR-INDIAB study, published in The Lancet Diabetes & Endocrinology in 2023, surveyed more than 113,000 adults across India. It estimated that in 2021, about 101 million people (11.4%) had diabetes and another 136 million (15.3%) had prediabetes.

Asian Indians also tend to carry more fat around the abdomen and may develop insulin resistance at a lower body weight. Being slim doesn’t guarantee safety. For South Asians, the International Diabetes Federation treats a waist of 90 cm or more in men, and 80 cm or more in women, as a sign of excess belly fat.

What Are the Symptoms of Prediabetes?

Most people with prediabetes have no symptoms at all, which is why it so often goes unnoticed. Some notice dark, velvety patches of skin on the neck, armpits or groin (acanthosis nigricans), which can point to insulin resistance.

When blood sugar becomes high enough, symptoms may appear:

• Increased thirst and frequent urination
• Unusual tiredness
• Blurred vision
• Slow-healing cuts or frequent infections
• Unplanned weight loss

Tiredness and cravings have many possible causes, so they can’t tell you whether you have insulin resistance. There is no single routine blood test used to diagnose insulin resistance; doctors assess your overall risk and may use glucose and other tests when appropriate.

Prediabetes Test: How Do You Check Where You Stand?

Prediabetes is found with a simple blood test. The ranges below follow the American Diabetes Association (ADA) criteria.

Test	What it shows	Normal	Prediabetes	Diabetes
HbA1c	Average sugar over about 3 months	Below 5.7%	5.7–6.4%	6.5% or higher
Fasting Blood Sugar	Sugar after at least 8 hours without food	Below 100 mg/dL	100–125 mg/dL	126 mg/dL or higher
2-hour OGTT	Sugar 2 hours after a 75 g glucose drink	Below 140 mg/dL	140–199 mg/dL	200 mg/dL or higher

A few things to keep in mind:

• HbA1c doesn’t need fasting, but fasting glucose does.

• The WHO uses 110–125 mg/dL for impaired fasting glucose, while the ADA uses 100–125 mg/dL for prediabetes. This difference is why the guideline used for interpreting a result matters.

• Conditions that affect red blood cells, such as anaemia or haemoglobin variants, can make HbA1c unreliable. Your doctor may then prefer a glucose test.

• Without clear symptoms, diabetes is usually confirmed with two abnormal results. One report doesn’t diagnose you.

Is there a test for insulin resistance?

No single routine test exists. Doctors sometimes measure fasting insulin with fasting glucose to calculate HOMA-IR, an estimate of insulin resistance. There is no universal cut-off. The reference range depends on the lab and method, and results are read alongside your waist size, blood pressure, cholesterol and family history. You don’t need HOMA-IR to diagnose diabetes, but it can help when a doctor wants a closer look.

At Redcliffe Labs, you can get HbA1c and fasting glucose tests individually or within diabetes check packages. HOMA-IR is also available if your doctor advises it.

Who Should Get Tested, and How Often?

The ADA recommends starting screening at age 35 for people who do not have other high-risk indications. Adults of any age with overweight or obesity (BMI 23 or above for people of Asian ancestry) and at least one additional risk factor should be considered for earlier testing, such as:

• A parent, brother or sister with diabetes
• PCOS
• High blood pressure
• High triglycerides or low HDL (“good”) cholesterol
• Diabetes during a past pregnancy
• A mostly inactive routine

If results are normal, repeat the test at least every three years, or sooner if your risk changes. With prediabetes, testing once a year is advised.

Can You Stop Prediabetes From Becoming Diabetes?

Often you can slow it down. Prediabetes is a warning, not a final diagnosis.

In the US Diabetes Prevention Program, 3,234 adults with overweight and higher-than-normal blood sugar were followed for about three years. An intensive lifestyle programme, aiming for about 7% weight loss and 150 minutes of activity a week, cut the risk of developing type 2 diabetes by 58% compared with placebo. Metformin cut it by 31%. In the Indian Diabetes Prevention Programme, lifestyle changes lowered the risk by 28.5% in Indian adults with impaired glucose tolerance. These are group results in high-risk people, not guarantees for any one person.

Simple steps that help:

• Move more: about 150 minutes a week of brisk walking or cycling, plus strength exercise on two days.

• Balance your plate: more vegetables, dal and whole grains, with smaller portions of white rice, maida and sweets.

• Swap sugary drinks and packaged juices for water, plain chaas or unsweetened nimbu pani.

• Aim for a healthier weight if you are overweight, since even modest loss helps.

• Protect your sleep and avoid tobacco.

Never start or stop a medicine without your doctor’s advice.

When Should You See a Doctor?

Speak to a doctor if you have risk factors and haven’t been tested, if a report shows borderline sugar, or if you notice excessive thirst, frequent urination, blurred vision or unplanned weight loss. Seek urgent care if high sugar comes with vomiting, stomach pain, fast breathing or confusion.

Know Your Numbers Before Your Body Tells You

Type 2 diabetes doesn’t begin with a high reading. It begins quietly, with insulin resistance, long before symptoms show. That early window is also the best time to act.

If you are 35 or older, or you have a family history, PCOS or a growing waistline, and haven’t checked your sugar in the past year, one test can show where you stand.

Take the first step with Redcliffe Labs:

• Book an HbA1c test to see your 3-month average.
• Choose a diabetes check package that bundles sugar tests with related checks.
• Add HOMA-IR if your doctor advises a closer look at insulin resistance.
• Home sample collection is available in many locations.

[Book Your Diabetes Test]

FAQS

1. Is insulin resistance the same as diabetes?

No. Insulin resistance means your cells respond poorly to insulin. Diabetes is diagnosed when blood sugar reaches a set level on tests like HbA1c or fasting glucose. Many people have insulin resistance for years before reaching that point, and some never develop diabetes.

2. Can I have insulin resistance even if my blood sugar is normal?

Yes. In early insulin resistance, the pancreas makes extra insulin to keep sugar in the normal range so that a report can look fine. Doctors look at waist size, blood pressure, cholesterol and family history, and sometimes fasting insulin, to judge your risk.

3. Can a thin person get type 2 diabetes?

Yes. Weight is a major risk factor but not the only one. Genes, age, family history, and fat stored around the belly also matter, and Asian Indians may develop diabetes at lower body weights. Normal weight doesn’t mean you can skip testing if you have other risk factors.

4. Do I need to fast for a prediabetes test?

It depends on the test. HbA1c needs no fasting. Fasting glucose needs at least 8 hours without food, though water is fine. HOMA-IR also needs fasting, usually 8–12 hours. Follow the instructions your lab gives you.

5. Does PCOS increase the risk of type 2 diabetes?

Yes. Many women with PCOS have insulin resistance, and the ADA lists PCOS as a risk factor for diabetes testing. If you have PCOS, ask your doctor how often to check your blood sugar.

6. Does prediabetes always turn into type 2 diabetes?

No. Prediabetes raises your risk, but it isn’t a certainty. In prevention trials, lifestyle changes lowered the number of people who progressed, and some people’s sugar returned to normal. Regular testing shows which way things are heading.

7. Will I need medicine if I have prediabetes?

Not always. Lifestyle changes are the first step. For some people at high risk, a doctor may consider medicine such as metformin, especially in younger adults, people with a higher BMI, higher blood glucose or A1C, or a history of gestational diabetes. Never start it on your own, because the decision depends on your age, weight, history and test results.