Diabetes Explained: A Complete Guide to Types, Symptoms, Treatments, and Prevention (With Quick-Reference Tables & FAQs)

What is Diabetes?

Diabetes is a chronic disease resulting in high blood glucose due to decreased insulin synthesis or reduced sensitivity to insulin. The prevalence rate of diabetes has been increasing at an alarming rate in developed countries. This is mainly due to the sedentary unhealthy lifestyle adopted by people living in urbanized areas.

Most people assume diabetes simply results in high blood sugar. In fact, the complications arising from diabetes can be deadly. It can result in permanent blindness, kidney failure, irreversible nerve damage, limb amputation, and death from diabetic ketoacidosis or hypoglycemia. This article aims to provide you with a comprehensive detailed knowledge about Diabetes, its causes, complications, and available treatments.

What is Insulin?

Insulin is a hormone essential for glucose uptake into the body’s cells. It is secreted by the Beta cells in the pancreas in response to the presence of food in our digestive tract. In type I diabetes, the body doesn’t synthesize insulin due to the autoimmune destruction of pancreatic cells. In type II diabetes, the body’s cells don’t respond to the normal levels of insulin.

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Insulin given to Diabetic patients is derived from the pancreas of a pig or cow. In diabetic patients, it is delivered into the body in the form of subcutaneous self-administered via needles, pumps, or reusable pens. A person born with type I Diabetes may have to administer insulin multiple times a day for the rest of their life. Not only is this costly, but if the dosage is not administered correctly it can result in serious complications due to hypoglycemia such as coma, seizures, brain damage, and death.

Classification of Diabetes and their associated Risk Factors

Type I Diabetes

It is an autoimmune disease that occurs when the body attacks the insulin-producing β-cell that are found in the pancreas. Destruction of β-cells results in decreased production of insulin that doesn’t satisfy the body’s requirement for insulin.

Risk factors for Type 1 are still being researched. However, having a family member with type I Diabetes slightly increases the risk of developing the disease. Environmental factors and exposure to some viral infections have also been linked to the risk of developing type I diabetes

Type 2- Diabetes

Type II Diabetes is the most common type of diabetes that usually occurs in adults. With an increasing number of children and adolescents suffering from obesity, type II diabetes incidence is increasing in children.

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It is characterized by a progressive insulin secretory defect wherein the body is producing insulin in a normal amount but the insulin sensitivity has decreased. The body is no longer able to respond to insulin, resulting in high blood glucose and decreased utilization of glucose by our cells.

Risk factors associated with Type II diabetes

• A family history of diabetes substantially increases the risk for both Type 1 and 2 diabetes
• Being overweight/obese is the most important contributing factor for Diabetes as the body loses its normal level of sensitivity to Insulin
• Unhealthy diets such as fast foods made with preservatives are rich in trans fatty acids and have high sugar content.
• Physical inactivity: A sedentary lifestyle with minimal exercise leads to obesity and hence to Diabetes.
• Increasing age: Diabetes is found in a large number of older people having unhealthy lifestyles with physical inactivity as the body’s normal metabolism also slows down with age.
• High blood pressure
• Ethnicity: People from American Indian, African-American, Asian-American, South Asian, Latino, or Pacific Islander are at higher risk of developing Diabetes
• Impaired Glucose Tolerance (IGT)*
• History of gestational diabetes: Women who developed gestational diabetes that later resolved after the end of pregnancy tend to develop Diabetes at an older age, especially in women who had a diet with poor nutrition during pregnancy.

Other specific types of diabetes

1. Genetic defects in β-cell function
2. Diseases of the exocrine pancreas
3. Drug- or chemical-induced
4. Gestational diabetes mellitus (GDM)

Diabetes at a Glance: Key Facts

How can T1DM and T2DM be differentiated?

Based on the age of onset and disease severity, Type I and Type II Diabetes can be easily differentiated. This differentiation is crucial as treatment choice varies depending on the type.

Type I Diabetes onset is typically below people of age 20 years, while Type II Diabetes starts late in people aged above 40 Years.

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Type I Diabetes tends to be more severe with serious complications such as Diabetic Ketoacidosis and Diabetic Coma.

Treatment of Type I Diabetes is always with insulin whereas Type II Diabetes can be treated with oral hypoglycemic drugs.

SYMPTOMS AND SIGNS OF DIABETES

Sometimes, Diabetes may present with no symptoms or signs. However, more often it presents with a typical triad of symptoms

1. Frequent urination – When levels of blood glucose rise beyond the threshold level, the kidneys excrete them out through the urine. In order to do so, the kidneys pull in water from the circulation to dilute the glucose. Hyperglycemia may lead to dehydration.
2. Increased thirst – The increased urge to urinate to eliminate the blood sugars results in increased water uptake by the Kidneys. To prevent dehydration, our body signals the need for more water intake, thereby causing increased thirst.
3. Increased hunger – Due to the decreased sensitivity of insulin, our cells are unable to take up glucose even though blood glucose levels are high. As the demand for energy by the cells is not fulfilled, the body craves more food.
4. Weight loss – With the cells not receiving their required energy from the diet, the breakdown of fatty acids and muscle results in weight loss.
5. Lethargy – Despite high blood sugar, the sugar is useless as an energy source as the cells are unable to take up any glucose leaving patients in a state of constant fatigue
6. Blurred vision – Hyperglycemia damages blood vessels and capillaries, which can result in diabetic retinopathy. Retinopathy initially presents as blurred vision, but can quickly progress to retinal detachment and blindness if not treated in time.

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Other rare but serious symptoms of diabetes include:

• A tingling sensation or numbness in the hands or feet
• Blurred vision
• Frequent infections
• Slow-healing wounds
• Vomiting and stomach pain (often mistaken as the flu)

Diagnosis

Diagnosis of Diabetes is pretty much straightforward as laboratory diagnosis of diabetes can quickly detect elevated blood glucose. Some of the tests done to diagnose diabetes are:

1. Blood Glucose (for diagnosis and monitoring)
2. Urine Glucose (for monitoring)
3. Insulin, C-Peptide
4. HbA1c (for monitoring)
5. Autoantibodies (for diagnosis of Type I DM)
6. Urine/ Blood Ketone Bodies (for diagnosing Diabetic Ketoacidosis)

Diagnostic criteria for Diabetes:

The WHO has set specific criteria for confirming whether a person has diabetes or isolated hyperglycemia. Having only one of the below laboratory values is sufficient to confirm a diagnosis of Diabetes:

1. 1. Fasting Blood Glucose: > 7 mmol/l
      OR
   2. Postprandial 2 hour Blood Glucose: >11.1 mmol/l
      OR
   3. Random Blood Glucose: >11.1 mmol/l
      OR
   4. HbA1c: >6.5%

What is HbA1c?

When glucose sticks to the hemoglobin, it makes a glycosylated hemoglobin molecule, which is called hemoglobin A1C or HbA1C. Its normal range is between 4%–6%. By measuring the HbA1C it can tell you how high your blood glucose has been on average over the last 8-12 weeks.

Complications of Diabetes

1. Diabetic Retinopathy

Diabetic retinopathy is the most common cause of new cases of blindness among adults 20-74 years of age. During the first two decades of disease, nearly all patients with type 1 diabetes and over 60% of patients with type 2 diabetes have retinopathy

2. Diabetic Ketoacidosis

DKA is an acute, life-threatening disorder that follows an imbalance between insulin levels and levels of counter-regulatory hormones.

Other complications of diabetes are polyneuropathy, nephropathy, and diabetic foot. These complications are due to high blood glucose levels damaging the nerves and blood vessels.

Treatment guideline for Diabetes

1. Closely monitor blood glucose levels

2. Diabetic Diet: Along with anti-diabetic medications, diet plays a crucial role in the treatment of Diabetes. Doctors recommend a diet comprising carbohydrates (50-60%), Protein(15-20%), and Lipid(20-25%).

3. Oral Antidiabetic Agents: Over the past few decades, Anti-Diabetic medications have evolved significantly. Based on the patient’s tolerance to side effects, one or more of the following medications are used as a treatment for controlling high blood sugar.

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• Sulfonylureas —— Stimulate insulin release from beta-cells of pancreatic islets. Adjuncts to diet and exercise to lower blood glucose in patients with type 2 diabetes mellitus. Examples: glyburide, glipizide, glimepiride.
• Glinides —— They lower blood glucose by stimulating pancreatic insulin release.
• Biguanides —— decrease hepatic glucose production, decrease intestinal absorption of glucose, and increase insulin sensitivity, therefore, increasing peripheral glucose uptake. Example: metformin.
• α glucosidase inhibitor —— Acarbose inhibits enzymes needed to digest carbohydrates. They may result in Gastro-Intestinal side effects—examples: acarbose, miglitol, and voglibose.
• Thiazolidiones —— Increase insulin sensitivity by affecting PPAR-γ (peroxisome proliferator-activated receptor) in adipose tissue, skeletal muscle, and in the liver. Example: rosiglitazone, pioglitazone.
• Dipeptidyl Peptidase-4 (DPP-4) Inhibitors: Inhibits the breakdown of GLP-1 by DPP-4, therefore, increasing.
• GLP-1 levels result in increased glucose-dependent insulin release and decreased levels of circulating glucagon and hepatic glucose production.

4. Insulin

In Type I Diabetes patients or in Type II Diabetes that is poorly controlled with oral antidiabetic drugs, Insulin injection subcutaneously is the treatment of choice. They are not the first choice in Type II diabetes as they can result in hypoglycemia (a decrease in blood glucose below 70mg/dl). Hypoglycemia can have serious debilitating effects on the Central Nervous System.

Diabetes FAQs on Prevention, Care, and Complications

1. Why is obesity a major risk factor for Type 2 diabetes?
Excess fat, especially visceral fat, causes insulin resistance by releasing inflammatory chemicals that disrupt insulin signaling.

2. Can Type 2 diabetes become Type 1 over time?
No. Type 1 is autoimmune and unrelated to Type 2. However, some Type 2 patients may eventually need insulin due to declining β-cell function.

3. What is diabetic neuropathy, and how does it start?
Nerve damage is caused by high blood sugar. Early signs include tingling/numbness in hands/feet, progressing to pain, ulcers, or amputations if untreated.

4. Why do some Type 2 diabetics still need insulin?
Over time, the pancreas’ β-cells wear out, reducing insulin production. Insulin becomes necessary when oral drugs fail to control glucose.

5. How does diabetic ketoacidosis (DKA) develop?
In Type 1 diabetes, insulin deficiency forces the body to burn fat, releasing toxic ketones. This causes life-threatening acidosis (vomiting, dehydration, coma).

6. Are insulin pumps better than injections?
Pumps deliver precise doses 24/7, mimicking natural insulin release. They reduce hypoglycemia risk but are costlier and require training.

7. Can diet alone reverse Type 2 diabetes?
In the early stages, weight loss (10–15% of body weight) and low-carb diets can restore insulin sensitivity, potentially achieving remission.

8. Why is HbA1c more reliable than daily glucose tests?
HbA1c reflects long-term glucose control (2–3 months), unaffected by daily spikes. Daily tests show real-time fluctuations for immediate adjustments.

9. How does gestational diabetes affect the baby long-term?
Babies face higher risks of obesity, Type 2 diabetes, and metabolic disorders later in life due to exposure to high glucose in the womb.

10. What’s the link between diabetes and blindness?
High glucose damages retinal blood vessels (retinopathy). Without treatment, this causes bleeding, retinal detachment, and permanent vision loss.

11. Are “natural” insulin alternatives (e.g., herbs) effective?
No. Insulin cannot be replaced by herbs or supplements. Some (e.g., cinnamon) may slightly improve insulin sensitivity but cannot cure diabetes.

12. Why do some diabetes medications cause weight gain?
Drugs like sulfonylureas and insulin promote glucose uptake into fat cells. Newer agents (e.g., GLP-1 agonists) often aid in weight loss.

13. Can diabetic foot ulcers be prevented?
Yes: daily foot checks, proper footwear, blood sugar control, and avoiding smoking reduce nerve damage and poor circulation risks.

14. What’s the role of exercise beyond weight loss?
Exercise increases insulin sensitivity, helps muscles absorb glucose without insulin, and improves cardiovascular health.

15. Are there breakthroughs in diabetes research?
Yes: Islet cell transplants (potential Type 1 cure), GLP-1/GIP dual agonists (better glucose control), and AI-driven glucose monitors.

References

National Institute of Diabetes and Digestive and Kidney Diseases. (n.d.). Diabetes. U.S. Department of Health and Human Services, National Institutes of Health. Retrieved [Month Day, Year], from https://www.niddk.nih.gov/health-information/diabetes

Johns Hopkins Medicine. (n.d.). Facts about Diabetes. https://www.hopkinsmedicine.org/health/conditions-and-diseases/diabetes