## All About Blood Glucose

Keeping your blood glucose (sugar) in your target range is one of the most important things you can do to feel your best and avoid future health problems. The good news is that most of what you need to do to take care of your diabetes is in your hands.

This includes following a meal plan, staying active, taking your medications, and doing your best to stay within your blood sugar target range.

 

 

 

   Watch Your Levels  

  Low Blood Sugar  

  High Blood Sugar  

  Diabetic Ketoacidosis (DKA)  

  When You’re Unwell  

 

 

 

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## Tracking Your Blood Sugar Numbers

To properly manage your diabetes, it’s important to keep track of your blood sugar numbers. You can do this in two ways:

- **Use a blood glucose meter** to check your levels throughout the day. Ask your healthcare team whether a Continuous Glucose Monitor (CGM) might be a good option for you.
- **Get an A1C test** at least twice a year to see your average blood sugar over the past few months.

These tools can help you and your care team know if your current plan is working, or if it needs to be adjusted.

 

 



 

## Making Sense of Your Numbers

Throughout the day, many factors can affect your blood glucose levels. Learning what influences these changes can help you better understand your body, make informed choices, and stay on track with your diabetes care.



 

 ### Why does my blood glucose level change—and what’s my healthy target range?

Your blood glucose level rises and falls throughout the day. One key to taking care of your diabetes is understanding why.

If you know the reasons, you can take steps to help keep your blood glucose on target:

American Diabetes Association (ADA) Targets for Blood Glucose (mg/dl)

Before a meal:

80–130

Two hours after beginning a meal:

Less than 180

 

  ### What can make blood glucose rise?

- A meal or snack with more food or more carbs than usual
- Physical inactivity
- Not enough diabetes medicine
- Side effects of other medicines
- Infection or other illness
- Changes in hormone levels, such as during menstrual periods
- Stress

 

  ### What can make blood glucose fall?

- Missing a meal or snack, or having a meal or snack with less food or fewer carbs
- More activity than planned
- Alcoholic drinks, especially on an empty stomach
- Taking insulin
- Taking too much medication

 

  ### How do you use a blood glucose meter?

Many people use a blood glucose meter to check their levels several times a day. Ask your healthcare team **when** and **how often** to check your blood glucose. They can give you a record book to keep track of your blood glucose numbers. You can learn how to use your numbers to make choices about food, physical activity, and medicines.

Your results tell you how well your diabetes care plan is working. You’ll be able to look at your record book and see patterns by looking for similar results that repeat. Looking at these patterns can help you and your healthcare team fine-tune your diabetes care plan to help you reach your targets.

 

  ### What is an A1C check?

The A1C tells you your average blood glucose level over the past two to three months. Your results will be reported in two ways:

- A1C as a percentage
- Estimated average glucose (eAG), in the same kind of numbers as your day-to-day blood glucose readings

Ask your healthcare team for this test at least twice a year.

**If your average blood glucose is too high, you may need a change in your diabetes care plan.**

 

  ### What does my A1C number mean?

In the table below, find your **A1C** number on the left. Then look at the number on the right to see your **estimated average glucose (eAG)** for the past two to three months:

A1C (%)

Estimated Average Glucose (eAG) (mg/dl)

5

97

6

126

7

154

8

183

9

212

10

240

11

269

12

298

 

  

 

 

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 ## Hypoglycemia

Low blood sugar, or hypoglycemia, can come on quickly, but you can take steps to feel better fast. Knowing the signs and how to treat them right away can help you stay safe and prevent more serious problems. **If low blood glucose isn’t treated quickly, it can lead to fainting and may require emergency medical care.**

**Causes:** Too little food or skipping a meal, too much insulin or diabetes medicine, or more activity than usual

**Onset:** Often starts suddenly

**Possible signs and symptoms:**

- Blurry vision
- Dizziness or headache
- Fast heartbeat
- Feeling anxious, irritable, or shaky
- Hunger
- Sweating
- Weakness and fatigue

### What Can You Do?

1. Check your blood glucose right away. A level of **70 or less** is considered low and requires treatment.
2. If you can’t check, **treat it anyway**:  
    **Eat:** three to four glucose tablets or three to five hard candies you can chew quickly (such as peppermints)  
    *or*  
    **Drink:** 4oz. (½ cup) of fruit juice or regular (not diet) soda
3. After 15 minutes, check your blood glucose again. If it is still under 80, treat again (take another round of one of the fast-acting glucose options from step 2).
4. If symptoms don’t stop, call your healthcare provider.

 

 



 

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 ## Hyperglycemia

High blood sugar, or hyperglycemia, can happen for many reasons—and it’s important to catch it early. Recognizing the signs and knowing what to do can help you take action before it becomes a more serious problem. **Very high blood glucose can become a medical emergency if not treated.**

**Causes:** Too much food; too little physical inactivity; not enough insulin or diabetes medicine; illness; increased stress

**Onset:** Often starts slowly

**Possible symptoms:**

- Blurry vision
- Dry skin
- Feeling drowsy
- Increased hunger and thirst
- Urinating frequently
- Wounds that seem to be healing slowly

### What Can You Do?

Keep checking your levels. If your blood sugar has been above your target for three days and you don’t know why, call your healthcare provider.

 

 



 

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 ## What Is Diabetic Ketoacidosis (DKA)?

##### Symptoms of DKA

- Breathing difficulty
- Drowsiness
- Extreme thirst
- Frequent need to urinate
- Fruity smell to the breath
- Nausea, stomach pain, and vomiting



**Diabetic ketoacidosis (DKA)** is a serious and potentially life-threatening complication of diabetes. It occurs when your blood becomes more acidic due to a buildup of **ketones**—acids that form when the body breaks down fat for fuel instead of glucose.

DKA can develop quickly, sometimes within hours. If left untreated, DKA can cause dehydration, trouble breathing, and in severe cases, coma. Fortunately, it can be prevented and treated when caught early.

**While DKA is commonly associated with high blood glucose, it can also happen at normal glucose levels—especially if you’re sick or dehydrated.**

 

 



 

## Triggers, Diagnosis, and Prevention

  ### Common Triggers

- **Infection or illness:** Your body needs more insulin when stressed.
- **Missed insulin doses:** Skipping insulin can lead to dangerously high blood sugar.
- **Insulin delivery issues:** Problems with insulin pumps or sets (like a kinked cannula).
- **Spoiled insulin:** Exposure to extreme temperatures can reduce insulin effectiveness.
- **Undiagnosed diabetes:** DKA may be the first sign of undiagnosed type 1 diabetes.



 

  ### Diagnosing DKA

##### Home Testing

Your **ketone level** can be an early warning sign of DKA. Testing your urine for ketones is an important part of staying safe when you’re ill or your blood sugar is high, so you can take action before the situation becomes serious.

If you are experiencing symptoms associated with DKA, or if you have blood glucose levels of more than 240 mg/dL that are not decreasing **even after taking insulin**, it is a good idea to test your urine for the presence of ketones.

##### Clinical Diagnosis

Your healthcare provider can test your blood to confirm DKA. The test will typically show:

- **High blood acidity** (low pH)
- **Presence of ketones**
- **Imbalances in electrolytes** like sodium and potassium



 

  ### How to Prevent It

- **Even when you’re not eating, your body needs insulin.** Always take your standard (basal) dose of insulin.
- **Check your blood glucose regularly**, or use a continuous glucose monitor (CGM).
- **Go ahead and test for ketones** if you have signs or symptoms of DKA, or your blood sugar stays over 240 mg/dL for longer than 3 hours even after taking insulin.
- **Create a back-up plan** with your diabetes team in case of insulin pump failure.
- **Get your flu shot every year** to reduce illness-related risk.



 

 

 

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## How Do You Test for Ketones?

You dip a special test strip in a sample of your urine and watch for a color change. The color result indicates a **trace** (close to zero), **small**, **moderate**, or **large** level of ketones.

##### If the Result Is “Trace” or “Small”

- **Drink 8 oz. (1 cup) of water** every hour.
- **Avoid exercise** if your glucose is over 240 mg/dL.
- **Take fast-acting insulin** if you have not done so in the past 3–4 hours.
- **Test your glucose and ketones** every 3–4 hours.
- **Call your healthcare provider** if your levels don’t improve after two rounds of testing.

##### If the Result Is “Moderate” or “Large”

- **Call your healthcare provider** or seek care immediately.
- **Drink 8 oz. (1 cup) of water** every hour.
- **Take fast-acting insulin** if you have not done so in the past 3–4 hours.
- **Keep testing** every two hours until you are cleared by your provider.

 

 



 

 Medication Note## SGLT2 Inhibitors and DKA Risk

Diabetes medications in the family of **SGLT2 inhibitors** (like Farxiga, Invokana, Jardiance, or Steglatro) can increase your risk of ketoacidosis *even when your glucose levels are normal*. Talk to your healthcare provider about **situations when you should avoid taking your SGLT2 medication**—for example, if you’re dehydrated, ill, planning strenuous physical activity, or eating a very low-carb diet.

**Be ready to test for ketones if you’re feeling unwell!**

 

 



 

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## How Other Illnesses Impact Your Diabetes

A “sick day” can include anything from a case of the flu (or even a common cold) to a stomach bug, infection, or recovery from an injury or surgery. When you have diabetes, being unwell can affect your blood sugar and how your medications work, so it’s important to know how to manage it.

When you’re ill, your body releases stress hormones. These hormones can raise your blood sugar and make it harder for your diabetes medications to work.

At the same time, you may be eating or drinking less, or losing fluids through vomiting or diarrhea, which can lead to dehydration and affect how your medications are absorbed.

 

 



 

## Sick Day Guidelines

  ### Pause Certain Medications

Do not take metformin (Glucophage), SGLT2 inhibitors (such as Empagliflozin, Jardiance, or Canagliflozin/Invokana), or sulfonylureas (such as glipizide or glimepiride) if you are vomiting or unable to eat and drink normally.



 

  ### Monitor Your Blood Sugar Frequently

Check your blood sugar every two to four hours—even during the night.



 

  ### Adjust Insulin as Needed

It’s a good idea to work with your healthcare provider in advance on a “sick day plan” for how to adjust your medication doses when you are unwell.

**You may need extra insulin.** If your blood sugar is over 240 mg/dL and you have type 1 diabetes or ketosis-prone diabetes, check your urine for ketones.

Watch for signs of dehydration. **If you are vomiting or have diarrhea, you may need** ***less*** **insulin.**

**Adjust your insulin with the guidance of a healthcare provider.**



 

 

 

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## When Should You Call Your Provider?

Call your health care provider if:

- You have a **fever** over 100°F for more than 24 hours that doesn’t improve with acetaminophen (Tylenol®).
- You’ve been **vomiting** or had **diarrhea** for more than six hours.
- You experience **stomach pain** or **trouble breathing**.
- Your **blood sugar stays above 240 mg/dl** for more than 24 hours—even after extra insulin and fluids.
- You have type 1 diabetes and have **moderate or large ketone levels** in your urine.
- You are not sure which medications to take.
- You’re unsure about what to do.

**If you can’t reach your provider, seek emergency care.**

 

 



 

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 The American Diabetes Association [recommends](https://diabetes.org/living-with-diabetes/treatment-care/checking-your-blood-sugar "Diabetes Testing & Monitoring: Check Your Blood Glucose | American Diabetes Association (diabetes.org)") blood glucose targets of **between 80 and 130 mg/dl** before meals and **below 180 mg/dl** two hours after the start of a meal.



 

 ## Explore the Resource Center

Learn how to manage your diabetes with our guides, tips, and videos.

 

- [← Back to Diabetes Resource Center](/diabetes-resource-center)
- [Eating Healthy](/diabetes-resource-center/eating-healthy)
- [Mindful Exercise](/diabetes-resource-center/mindful-exercise)
- [Medicine for Diabetes](/diabetes-resource-center/medicine-for-diabetes)
- [Managing Complications](/diabetes-resource-center/managing-complications)
- [Mental Health Care](/diabetes-resource-center/mental-health-care)
 
 

 

 *Diabetes information found on these pages should not replace education or instruction from your healthcare provider or certified diabetes educator. We encourage all patients to personalize their diabetes management in collaboration with their healthcare team.*