If your HbA1c (glycated hemoglobin) is below 6%—which means your average blood sugar for the past 2–3 months has been normal—but your random blood glucose (RBG) test comes out high, you might be confused or worried. Does this mean you have diabetes? Here’s what you need to know:

What Do HbA1c and RBG Actually Show?

• HbA1c: Reflects your average blood sugar over the past 2–3 months. If it’s <6%, it usually means you are not diabetic.

• RBG (Random Blood Glucose): Measures blood sugar at any time of day, regardless of meals, stress, illness, or recent activity. This level can fluctuate a lot based on what and when you’ve eaten, medications, acute illness, or stress.

Why Can RBG Be High If HbA1c Is Normal?

• Short-term Spikes Don’t Show in the Average: HbA1c reflects long-term average, so a few high readings (from sweets, illness, or even stress) may not raise your overall average.

• Meal or Snack Before Test: If you eat something sugary or high in carbs shortly before the test, RBG may be temporarily high.

• Temporary Body States: Infection, stress, or certain medicines can temporarily increase blood sugar even if your average is fine.

• Repetitive Spikes: If high random readings happen often, over time they may raise your HbA1c. Repeated spikes can still cause harm to blood vessels and nerves even if your average is still "normal".

What Should You Do?

• Don’t panic after one high RBG value. Instead:

  • Monitor your blood sugar at different times (fasting, after meals, and randomly) for a few days.

  • If RBG readings are repeatedly above 200 mg/dL, consult your doctor.

• Further Testing: Your doctor may recommend an OGTT (oral glucose tolerance test) or fasting blood sugar test to get a clearer picture.

• Lifestyle Changes: To avoid sudden spikes, limit sweets and refined carbs, eat more fiber-rich foods, exercise regularly, and manage stress.