What Affects Blood Sugar: Factors Of Blood Sugar Swings

Discover what affects your blood glucose and how to keep your levels at a steady, healthy range.

April Benshosan
— Signos
Health Writer
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Reviewed by

April Benshosan
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Updated by

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Science-based and reviewed

July 19, 2024
December 23, 2023
— Updated:

Table of Contents

Blood glucose levels tell you how much sugar is circulating in your blood. Your levels can be affected by multiple different factors, including what you ate, how much exercise you got, whether you drank alcohol and more. When your blood sugar spikes, insulin kicks in to help bring your levels back down to a healthy range. But when your blood sugar is too low, it's up to you to refuel with fast-acting carbs (like fruit or candy). Basically, managing your blood sugar swings—whether or not you have type 1 diabetes or type 2 diabetes—is vital for preventing weight gain, heart health issues, and other health problems. 

Here's everything you need to know about what affects your blood sugar and how to keep your levels at a steady, healthy range.


What Affects My Blood Glucose Levels?

It's perfectly normal for your blood glucose levels to rise and fall. Fluctuations can be caused by a variety of different factors, like eating a bowl of pasta or doing an intense workout; but blood sugar ebbs and flows can also be triggered by variables outside of your control, such as stress and hormone changes. 

Factors That Cause Blood Glucose to Rise Include:

  • Consuming More Carbohydrates Than Usual<p style="margin: 0;">There are three main types of carbohydrates: sugar, starch, and fiber. When you sit down to a meal or snack that's high in carbohydrates, especially refined carbs that are devoid of fiber, your blood sugar levels will likely skyrocket. When you eat carb-rich foods, your body breaks down the sugars and starches into simple sugars, which enter your bloodstream and trigger an uptick in blood sugar levels. However, fiber doesn't cause blood sugar to rise because it isn't digestible, and because of this, fiber can steady your blood sugar levels rather than spiking them<p>
  • Side Effects of Medications<p style="margin: 0;">Certain medications can cause your blood sugar levels to rise, which is known as drug-induced or drug-associated hyperglycemia (or high blood sugar). Some of these meds include fluoroquinolones (a type of antibiotic), beta-blockers and thiazide antihypertensive drugs (which are used to lower blood pressure), certain antipsychotics, corticosteroids, CNI inhibitors (a type of immunosuppressant), and protease inhibitors (used to manage HIV)<p>
  • Infection or Other Illness<p style="margin: 0;">When you're sick, your body produces the stress hormones adrenaline (also known as epinephrine) and cortisol. These hormones are responsible for bolstering your immune system to help fight off a pesky virus or bacteria, but they can also cause your blood sugar to spike<p>
  • Hormonal Changes<p style="margin: 0;">Hormone fluctuations, which occur when you're about to get your period or during menopause, can cause changes in your blood sugar levels. A few days before your period, levels of the hormone progesterone increase, which can cause your blood glucose to rise along with it. 
    What's more, going through menopause can affect your blood glucose since lower estrogen levels can sometimes lead to insulin resistance, causing higher blood sugar levels. While this isn't the case for everyone, you can track your blood sugar levels during your menstrual cycle with the help of a continuous glucose monitor, or CGM<p> 
  • Stress<p style="margin: 0;">Stress messes with your hormone levels, causing cortisol and adrenaline (the same two hormones that your body also produces when you're sick) to shoot up. But anxiety also causes rises in other stress hormones, including glucocorticoids and catecholamines, which can contribute to high blood sugar and type 2 diabetes in the long run. In fact, research has found that chronic stress is linked to a higher risk of diabetes. That's one of the many reasons why it's so important to manage your stress levels1, 2, 3, 4, 5<p>

<p class="pro-tip"><strong>Learn more: </strong><a href="/blog/how-to-break-a-fast">How to Break a Fast Safely: Managing Blood Sugar Levels</a>.</p>

Factors That Cause Blood Glucose to Fall:

  • Ingesting Fewer Carbohydrates Than Usual<p style="margin: 0;">Digestible carbs — as in sugar and starches — get broken down into simple sugars in your body. This causes your blood sugar to rise, triggering the pancreas to release insulin, a hormone that helps your cells absorb the sugar in your blood for energy. But if you're eating too few carbohydrates, you may end up with Hypoglycemia, or low blood sugar levels, which causes symptoms including fatigue, hunger, rapid heartbeat, mental health issues like irritability, and others<p>
  • Extra Activity<p style="margin: 0;">Exercising is a fantastic way to maintain your health, whether you live with diabetes or not. However, people living with diabetes need to be picky with the workouts they choose to partake in. Prolonged exercise (think: endurance training) can cause your body's levels of stored glucose (i.e., glycogen stores) to become depleted, leading to low blood sugar. If you're training for a marathon, going on a long hike, or planning to be active all day, make sure to refuel with a healthy carb-rich snack to avoid hypoglycemia<p> 
  • Missing a Meal or Snack<p style="margin: 0;">Hunger is a tell-tale sign of low blood sugar. Skipping meals or forgetting to bring snacks with you when you're out can potentially lead to low blood glucose levels, which is especially risky for people with diabetes. If you're on insulin therapy to lower your blood sugar, skipping meals can cause your blood sugar to drop to dangerously low levels. If you usually take insulin with your meals, you'll want to skip the mealtime insulin if you forgo food — but if you often skip meals, talk to your healthcare provider about adjusting your medications<p>
  • Side Effects of Medications<p style="margin: 0;">Certain medications, such as insulin, can cause your blood glucose levels to drop, aka drug-induced low blood sugar. Many of these medications are, unsurprisingly, used to treat diabetes and include insulin, glinides, sulfonylureas, and SGLT2 inhibitors. 
    But other non-diabetes-related meds can also cause blood sugar dips. These include beta-blockers, cibenzoline and quinidine (which are used to treat heart arrhythmia drugs), indomethacin (a pain reliever), and certain infection-fighting drugs (such as gatifloxacin, levofloxacin, pentamidine, and quinine)<p>
  • Drinking Alcoholic Beverages<p style="margin: 0;">Your liver is responsible for breaking down alcohol. When you drink a cocktail, beer, or wine, your liver prioritizes metabolizing the alcohol first and therefore stops releasing glucose. And that causes your blood glucose levels to plummet. This makes it especially dangerous for people on diabetes medications, which already lower their blood sugar. To help prevent your blood sugar levels from dipping too low, drink less alcohol and remember to eat along with it<p> 

How to Prevent Blood Sugar Spikes


It's important to keep your blood sugar levels stable because, over time, hyperglycemia can cause damage to your blood vessels, which can increase your risk of heart attack, heart disease, stroke, kidney disease, and other diabetes complications. However, making a few lifestyle changes and tweaking your routine can help prevent high blood glucose and keep your levels healthy. 6, 7

Here are a few ways to help prevent blood sugar spikes: 

  • Try a Low-Carb Diet<p style="margin: 0;">Sugars and starches (two types of digestible carbs in food) get broken down into sugars in your body, which is what causes your blood sugar levels to rise. Going on a low-carb meal plan can therefore help decrease those spikes. In fact, research shows that reducing carb intake to no more than 130 grams of carbs per day helped people with diabetes reduce their HbA1c as well as their BMI<p>
  • Eat Fewer Refined Carbs<p style="margin: 0;">Going low-carb doesn't mean you have to forgo fruits and whole grains altogether—instead, focusing on limiting or avoiding refined carbs is a better bet when it comes to optimizing your diet for healthier blood sugar. Refined carbs include those that have been heavily processed and stripped of important nutrients, such as blood sugar-stabilizing fiber. Refined carb foods include white bread, white rice, regular pasta, pastries and baked goods, soda, and candy. These processed picks have a high glycemic index, which means they spike your blood sugar the most, so they're best enjoyed in moderation<p>
  • Eat Less Sugar<p style="margin: 0;">When you're limiting your overall carbohydrate intake, it's important to focus on reducing sugar. Sugar is a type of refined carb that, on its own, can cause blood sugar levels to skyrocket fast. Always check your food package labels for added sugar content, and aim to eat as little added sugar as possible<p> 
  • Lose Weight if You Need To<p style="margin: 0;">Being overweight or obese can cause type 2 diabetes because your body isn't as efficient at using insulin, which helps keep blood sugar levels stable. If you already have diabetes, losing weight can help you maintain lower blood sugar levels. And if you don't have diabetes but are overweight or obese, losing the extra pounds can help reduce your risk of developing prediabetes<p>
  • Fit Exercise Into Your Day<p style="margin: 0;">Working out—whether that's lifting weights, going for a run, or any other physical activity—can help make your body more sensitive to insulin (or increase your insulin sensitivity). Exercising also lowers your blood sugar levels for up to a full day following your workout. Make time to fit regular physical activity into your day—doing so can also help you lose weight, which, on its own, can help promote healthier blood sugar levels<p>
  • Stay Hydrated<p style="margin: 0;">Drinking more water is linked to lower blood sugar levels. That's because when you're dehydrated, your body produces a hormone called vasopressin, which causes elevated blood sugar and high blood pressure. While how much water you should drink per day mostly depends on your size and activity status, one study found that drinking at least 1 liter (or 4.2 cups) of H2O per day was linked to lower blood sugar levels8, 9, 10, 11<p>

Learn More About How to Improve Blood Sugar Health With Signos’ Expert Advice

Understanding how certain foods and lifestyle habits affect your blood sugar levels is key to helping you manage your diabetes or prevent developing the disease down the line. Signos can help arm you with the information you need to optimize your diet, lose weight, and learn about the different medications available to help you live a healthier life. To learn more about glucose levels, check out Signos’ blog.

Ready to try CGMs? Take this quick quiz to find out if Signos is right for you.

<p class="pro-tip"><strong>Keep reading: </strong><a href="/blog/low-sugar-drinks">11 Refreshing Low-Sugar Drinks That Won't Spike Blood Sugar</a>.</p>

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About the author

April is a writer, editor, and content strategist with a Master’s degree in Publishing.

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