Type 2 Diabetes Mellitus
Type 2 Diabetes is a chronic metabolic condition characterized by insulin resistance. Over time, the body's inability to effectively use insulin leads to persistently elevated blood glucose (hyperglycemia), which causes systemic microvascular and macrovascular damage.
Diagnostic Criteria
Diabetes is primarily diagnosed using one of three blood tests. The American Diabetes Association (ADA) defines the thresholds as follows:
| Test Type | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| HbA1c | Below 5.7% | 5.7% to 6.4% | 6.5% or higher |
| Fasting Plasma Glucose (FPG) | 99 mg/dL or below | 100 to 125 mg/dL | 126 mg/dL or higher |
| Oral Glucose Tolerance (OGTT) | 139 mg/dL or below | 140 to 199 mg/dL | 200 mg/dL or higher |
Pathophysiology: The Mechanism of Damage
When blood sugar remains chronically high, glucose molecules physically attach to proteins in the blood (glycation). This process damages the inner lining of blood vessels (the endothelium).
- Microvascular Damage: Affects the smallest blood vessels, leading to retinopathy (blindness), nephropathy (kidney failure), and neuropathy (nerve damage, often in the feet).
- Macrovascular Damage: Affects large arteries, exponentially increasing the risk of coronary artery disease, heart attacks, and strokes.
First-Line Management
Type 2 diabetes is unique in that it is heavily mediated by lifestyle factors, and in early stages (prediabetes), it can often be halted or reversed.
1. Lifestyle Interventions
- Weight Loss: A sustained weight loss of 5-10% of body weight significantly improves insulin sensitivity.
- Dietary Modification: Prioritizing complex carbohydrates with low glycemic indices, lean proteins, and reducing processed sugars.
- Exercise: Skeletal muscle is the primary sink for glucose. Strength training and aerobic exercise both lower blood sugar independent of insulin.
2. Pharmacological Foundations
If lifestyle changes are insufficient, Metformin is almost universally the first-line medication. It works by decreasing hepatic (liver) glucose production and increasing muscle insulin sensitivity. It is widely considered safe, effective, and weight-neutral. Newer drug classes (GLP-1 receptor agonists and SGLT2 inhibitors) are frequently prescribed for patients with high cardiovascular or renal risk profiles.
Interpret Your Labs
Convert your HbA1c percentage into an Estimated Average Glucose (eAG) in mg/dL to better conceptualize your daily blood sugar levels.
Open A1C Converter