Overview of Diabetes
Diabetes is a chronic condition where the body can't properly regulate blood glucose levels. Because nearly every drug in this unit targets some part of glucose metabolism, understanding the underlying disease is the foundation for everything that follows.
Type 1 vs. Type 2 Diabetes Mechanisms
Type 1 diabetes is an autoimmune disorder. The immune system attacks and destroys the insulin-producing beta cells in the pancreas, leaving the body with little or no insulin production. Without insulin, glucose can't enter cells, so it builds up in the blood. Patients with Type 1 always require exogenous insulin (via injections or an insulin pump) to survive.
Type 2 diabetes works differently. Here, the body still produces insulin, but cells become resistant to its effects. The pancreas tries to compensate by making more insulin, but over time it can't keep up, and blood glucose rises. Type 2 is strongly associated with obesity, physical inactivity, and genetic factors. Treatment typically starts with lifestyle changes (diet and exercise) and oral medications like metformin, though some patients eventually need insulin as well.
Key distinction for pharmacology: Type 1 = no insulin production → must give insulin. Type 2 = insulin resistance ± declining production → multiple drug classes can help.
Common Signs and Symptoms
The classic triad of diabetes symptoms all stem from excess glucose in the blood:
- Polyuria (increased urination): The kidneys can't reabsorb all the excess glucose, so it spills into the urine and pulls water with it.
- Polydipsia (increased thirst): Fluid loss from polyuria triggers thirst to compensate for dehydration.
- Polyphagia (increased hunger): Cells are starved for glucose they can't take up, so the body signals for more food.
Other common symptoms include:
- Unexplained weight loss, especially in Type 1, as the body breaks down fat and muscle for energy when it can't use glucose
- Fatigue and weakness from inefficient glucose utilization by cells
- Blurred vision caused by fluid shifts in the lens of the eye when blood glucose is high
- Slow-healing wounds and frequent infections (UTIs, yeast infections), because elevated glucose impairs immune function and tissue repair
Causes and Diagnosis of Diabetes
Causes of Diabetes
Type 1 results from a combination of genetic predisposition and environmental triggers (such as viral infections) that set off an autoimmune attack on pancreatic beta cells. It most commonly presents in childhood or adolescence, though it can develop at any age.
Type 2 involves both genetic susceptibility and modifiable lifestyle factors. Obesity, physical inactivity, and an unhealthy diet all contribute to worsening insulin resistance and declining insulin production over time. It accounts for roughly 90–95% of all diabetes cases.
Diagnostic Tests
Four blood tests are used to diagnose diabetes. A diagnosis typically requires two abnormal results on separate occasions, unless the patient has classic symptoms with a clearly elevated random glucose.
| Test | What It Measures | Diagnostic Threshold |
|---|---|---|
| Fasting Plasma Glucose (FPG) | Blood glucose after an 8-hour fast | ≥ 126 mg/dL (7.0 mmol/L) |
| Oral Glucose Tolerance Test (OGTT) | Blood glucose 2 hours after drinking a 75 g glucose solution | ≥ 200 mg/dL (11.1 mmol/L) |
| Glycated Hemoglobin (A1C) | Average blood glucose over the past 2–3 months | ≥ 6.5% (48 mmol/mol) |
| Random Plasma Glucose | Blood glucose at any time of day | ≥ 200 mg/dL (11.1 mmol/L), with classic symptoms |
The A1C is especially useful because it doesn't require fasting and gives a picture of long-term glucose control rather than a single snapshot. You'll see A1C referenced constantly when monitoring how well a patient's diabetic drug regimen is working.