Can Low Blood Sugar Make You Tired?

Aug 9

Written By Scott Theroux

You suddenly feel drained.

Your legs feel weak. Your concentration disappears. Maybe you feel like you could close your eyes and fall asleep.

If you have Type 2 diabetes, you may wonder:

“Is my blood sugar too low?”

It could be.

Low blood sugar—also called hypoglycemia—can absolutely cause tiredness, weakness, and sleepiness.

But fatigue alone can't tell you whether your glucose is low.

That distinction matters because high blood sugar can also make you tired, and many other problems can cause fatigue.

So instead of guessing from how you feel, the goal is to recognize the warning signs, check your glucose when possible, treat a true low promptly, and then figure out why it happened.

The Short Answer

For many people with diabetes, blood glucose below 70 mg/dL is considered low.

Symptoms can come on quickly and may include:

Tiredness or weakness
Sleepiness
Shakiness
Sweating
Hunger
Dizziness or lightheadedness
Fast heartbeat
Irritability
Headache
Confusion
Blurred vision

Very low glucose can progress to seizures or loss of consciousness and requires immediate treatment.

The most useful rule for this article is:

Treat first. Troubleshoot second.

If your glucose is actually low, figuring out why can wait until the immediate low has been addressed safely.

Why Can Low Blood Sugar Make You Feel So Tired?

Your body depends on a steady supply of glucose.

When blood glucose falls too low, your body responds quickly.

That's why a low doesn't always feel like ordinary end-of-the-day tiredness.

It may feel more sudden:

“Five minutes ago I was okay. Now I feel weak, shaky and completely drained.”

The American Diabetes Association notes that some symptoms—such as sweating, a racing heart, nervousness and shakiness—are related to the body's release of adrenaline as glucose falls.

Other symptoms can include sleepiness, weakness, confusion and having little or no energy.

That gives us an important distinction:

Low blood sugar fatigue often has company.

If tiredness suddenly appears alongside shakiness, sweating, hunger or dizziness, glucose becomes especially important to check.

If you regularly wake exhausted despite spending enough time in bed, read our guide to [Type 2 diabetes and sleep apnea.]

What Blood Sugar Number Is Too Low?

For most people with diabetes:

Below 70 mg/dL = low blood sugar

Your personal treatment plan may differ, so follow the glucose targets given to you by your healthcare team.

A glucose level below 54 mg/dL represents a more serious level of hypoglycemia. Severe hypoglycemia can also be defined by the person's inability to treat themselves and need for someone else's assistance.

This isn't a number to simply watch and wait on.

Low glucose deserves prompt attention.

Don't Use Tiredness as Your Glucose Meter

This may be the most important lesson in the article.

Imagine two afternoons.

Afternoon A

You feel tired, thirsty and are urinating more than usual.

Your glucose is elevated.

Afternoon B

You suddenly feel tired, shaky, hungry and sweaty.

Your glucose is low.

The word “tired” appears in both situations.

The cause is completely different.

That's why symptoms are clues—not measurements.

If glucose monitoring is part of your diabetes care plan, checking gives you much better information than trying to identify high or low glucose based only on how you feel.

For the other side of this question, read:

Does High Blood Sugar Make You Tired? What to Check

Can You Feel “Low” Even When You're Above 70?

Yes—and this is something many people don't realize.

The ADA notes that some people can experience symptoms that feel like hypoglycemia even when glucose is above 70 mg/dL.

This can happen when glucose has been running high and then begins falling quickly, or when someone accustomed to chronically higher glucose levels begins moving toward their target range.

That does not necessarily mean the person has true hypoglycemia.

So don't automatically start chasing the symptoms with large amounts of sugar without knowing what your glucose is doing when you're able to check.

If this keeps happening, bring the pattern to your diabetes care team.

Why Does Low Blood Sugar Happen in Type 2 Diabetes?

This is where we need to avoid another common misconception:

Having Type 2 diabetes does not mean you're automatically going to have frequent lows.

Risk depends heavily on treatment and circumstances.

NIDDK specifically identifies insulin and certain medicines that stimulate insulin release—such as sulfonylureas and meglitinides—as medications that can contribute to hypoglycemia.

Other situations can increase risk too.

1. Missing or Delaying a Meal

If medication, food and timing don't line up as expected, glucose can fall.

Skipping meals or eating fewer carbohydrates than usual can be especially relevant for people taking medications capable of causing hypoglycemia.

2. More Physical Activity Than Usual

Exercise can lower glucose during activity and for hours afterward.

NIDDK notes that increased activity may influence blood glucose for as long as 24 hours afterward.

That's why a low at 8 PM might sometimes be connected to something you did much earlier in the day.

3. Alcohol

Alcohol can make it harder for the body to keep glucose steady, particularly when someone drinks without enough food.

It can also make early hypoglycemia symptoms harder to notice.

4. Illness or Eating Less Than Usual

Being sick can change appetite, food intake, activity and medication needs.

If you aren't eating normally but continue taking glucose-lowering medication, the situation may require guidance from your healthcare team.

5. Changes in Your Normal Routine

Unexpected differences in meals, exercise, medication timing or daily schedule can sometimes upset a routine that normally keeps glucose stable.

The key is not to panic over one low.

It's to figure out whether there's a repeatable trigger.

Can Blood Sugar Drop While You Sleep?

Yes.

And nighttime hypoglycemia deserves attention because you may not wake up when it happens.

Possible clues include:

Nightmares or crying out during sleep
Waking with sweaty sheets or pajamas
Feeling tired, irritable or confused in the morning

NIDDK notes that nighttime lows can interfere with sleep and affect mood, quality of life and the ability to function the following day.

So if you repeatedly wake up feeling unusually exhausted—especially if you're at risk for hypoglycemia—don't automatically assume you simply slept badly.

Discuss the pattern with your healthcare team.

What Should You Do If Your Blood Sugar Is Low?

This is where we follow established medical guidance rather than inventing a Health & Fitt method.

For a glucose reading below 70 mg/dL, the ADA recommends the 15-15 Rule for most conscious adults who can safely swallow:

1. Take 15 grams of fast-acting carbohydrate.

Examples can include glucose tablets, glucose gel, about 4 ounces of juice or regular soda, or another fast-acting source specified in your treatment plan.

2. Wait 15 minutes.

3. Check your glucose again.

If it's still below 70 mg/dL, take another 15 grams of fast-acting carbohydrate and repeat the process.

Once glucose has recovered, follow the plan your healthcare team has given you for preventing another drop.

One common mistake

Chocolate or peanut butter might contain carbohydrates, but the fat and protein can slow digestion.

The ADA recommends fast-acting carbohydrate for treating a low rather than relying on slower foods when a quick rise is needed.

The Health & Fitt Low-Blood-Sugar Pattern Check

This comes after the low has been safely treated.

It's an educational framework—not a diagnostic tool.

Remember:

Number → Timing → Trigger → Repeat

1. Number

What was your actual glucose reading?

Write it down.

2. Timing

When did the low happen?

Before breakfast?

Several hours after eating?

During exercise?

Later that evening?

While sleeping?

Timing can reveal useful clues.

3. Trigger

Ask what was different that day:

Did I delay a meal?
Eat less than usual?
Exercise more?
Drink alcohol?
Take medication at a different time?
Feel sick?

Don't assume the answer.

Just collect evidence.

4. Repeat

Has this happened once—or repeatedly?

One unusual low may have an obvious explanation.

Repeated lows deserve a conversation with your healthcare professional because the treatment plan may need reviewing. NIDDK and CDC both advise working with the healthcare team rather than changing diabetes medication on your own.

This is the mental model I want readers to remember:

Treat the low first. Study the pattern afterward.

What If You Keep Having Low Blood Sugar?

Don't simply compensate by eating extra sugar all day or deliberately keeping glucose high.

And don't reduce or stop prescribed medication by yourself.

Instead, bring your records to your healthcare professional.

Useful information includes:

Time of the low
Glucose reading
Medication timing
Recent meals
Physical activity
Alcohol
Symptoms
Whether another person had to help you

That gives your healthcare team something concrete to work with.

Repeated lows can also lead to hypoglycemia unawareness, where the usual warning symptoms become harder to recognize. That increases the risk of severe hypoglycemia.

When Low Blood Sugar Is an Emergency

Severe hypoglycemia is an emergency.

Someone may become:

Severely confused
Unable to swallow safely
Unable to treat themselves
Unconscious
Having a seizure

In that situation, do not try to force food or drink into the person's mouth if they cannot swallow safely.

Glucagon is used for severe hypoglycemia when available, and emergency medical help may be required. The ADA advises calling 911 when necessary, including when someone is unconscious and glucagon is unavailable or cannot be given.

People at risk for severe hypoglycemia should discuss having glucagon available and making sure family members or others close to them know how to use it.

What If I'm Tired but My Blood Sugar Isn't Low?

Zoom out.

If you're frequently exhausted and your glucose isn't low when the fatigue occurs, don't keep trying to make hypoglycemia fit the symptoms.

There are many other possibilities.

Your broader guide covers:

High blood sugar
Hydration
Sleep
Diabetes treatment
Other possible causes of fatigue

Read:

Why Am I Always Tired With Type 2 Diabetes?

Not sure when fatigue deserves medical attention? Read our guide to "when you should talk to a doctor about diabetes fatigue".

Frequently Asked Questions

Can low blood sugar make you sleepy?

Yes. Sleepiness, weakness and having little energy can occur during hypoglycemia. But sleepiness alone does not confirm that your glucose is low.

Is 70 blood sugar too low?

For most people with diabetes, glucose below 70 mg/dL is considered low and should be addressed according to their hypoglycemia treatment plan. Individual targets can differ.

Can low blood sugar make you weak and shaky?

Yes. Weakness and shakiness are recognized symptoms of hypoglycemia, along with sweating, hunger, dizziness and confusion.

Why do I feel low when my glucose isn't below 70?

Some people experience low-glucose symptoms when their glucose is falling rapidly from a previously high level even though it remains above 70 mg/dL. Discuss repeated episodes like this with your diabetes care team.

Can I have low blood sugar after eating?

It can happen depending on medications, meal timing and other circumstances. But simply feeling tired after eating does not prove hypoglycemia.

For the larger question, read:

Why Am I Tired After Eating With Type 2 Diabetes?