Type 2 Diabetes Mellitus — Symptoms, Diagnosis and Management

Type 2 diabetes is one of the most common conditions I see in practice, and many patients only discover it by accident, during a routine blood test or when a wound refuses to heal.

The good news is that it is manageable, and often preventable. The earlier it is found, the better the outcome.

What is type 2 diabetes?

Type 2 diabetes is a chronic condition in which the body cannot use insulin properly. This is called insulin resistance. At first, the pancreas compensates by producing more insulin. Over time it cannot keep up, and blood sugar rises above normal.

It accounts for the large majority of all diabetes cases and usually develops in adults, although it is increasingly seen in younger people.

Symptoms and risk factors

Symptoms develop slowly and are easy to ignore. The common ones are:

• Increased thirst and frequent urination
• Constant hunger and unexplained weight loss
• Fatigue and blurred vision
• Slow-healing cuts and frequent infections
• Tingling or numbness in the hands and feet
• Dark, velvety skin patches around the neck or armpits (acanthosis nigricans)

Risk factors that I look for in every patient include:

• Overweight or obesity, especially abdominal fat
• A parent or sibling with diabetes
• Physical inactivity
• Age above 45
• Prediabetes, hypertension, or high cholesterol
• Gestational diabetes or polycystic ovary syndrome (PCOS)

How is it diagnosed?

Diagnosis is based on blood tests. Using the American Diabetes Association (ADA) criteria, diabetes is diagnosed when any of the following is present:

• Fasting blood sugar (FBS): 126 mg/dL (7.0 mmol/L) or higher, after at least 8 hours of fasting
• HbA1c: 6.5% or higher, reflecting average blood sugar over about 3 months
• Oral glucose tolerance test (OGTT): 2-hour value of 200 mg/dL (11.1 mmol/L) or higher after a 75 g glucose load
• A random blood sugar of 200 mg/dL or higher with classic symptoms

Without clear symptoms, the result should be confirmed with a repeat test. Values between 100 and 125 mg/dL (fasting) or an HbA1c of 5.7–6.4% indicate prediabetes, which is the best time to act.

How is it managed?

Management starts with lifestyle. Losing even 5–10% of body weight, eating fewer refined carbohydrates and sugary drinks, and doing about 150 minutes of moderate exercise per week can improve blood sugar significantly.

When medication is needed, metformin remains the usual first-line drug. It lowers glucose production in the liver, improves insulin sensitivity, is inexpensive, and does not typically cause weight gain. Common side effects are stomach upset and diarrhea, which often settle with a gradual dose increase.

If targets are not met, or if the patient has heart disease, heart failure, or kidney disease, we add other agents such as SGLT2 inhibitors or GLP-1 receptor agonists. Insulin is used when needed. For most adults, the usual HbA1c target is below 7%, though I individualize it based on age and other illnesses.

Regular monitoring matters too: HbA1c every 3–6 months, along with blood pressure and cholesterol control.

Complications to prevent

Persistently high blood sugar damages small and large blood vessels. The main complications are:

• Heart attack and stroke
• Diabetic retinopathy, which can lead to blindness
• Diabetic nephropathy and chronic kidney disease
• Peripheral neuropathy and foot ulcers, sometimes ending in amputation

Prevention means good glycemic control, an annual eye examination, yearly urine albumin and kidney function tests, and daily foot checks. Stopping smoking is equally important.