Metabolic Health

Why You Should Pay Attention to Blood Glucose Levels After Eating

5 minutes read

Monitoring your glucose levels can tell you a lot about your personal response to foods and activities, even for non-diabetics. While your fasting glucose levels are often measured to check for prediabetes or diabetes, your glucose response after eating a meal — also known as your postprandial glucose levels — is an important indicator of your metabolic health. 

Postprandial glucose levels that are consistently higher than normal are associated with conditions like glucose intolerance, insulin resistance, cardiovascular disease, and type 2 diabetes. On a day-to-day level, glucose spikes after eating can have a negative effect on your energy, mood, and ability to maintain a healthy weight. But what exactly is the ideal glucose range after eating, and what can you do to stabilize your levels?

What are postprandial (post-meal) glucose levels?

Your postprandial glucose levels measure the amount of glucose in your bloodstream two hours after a meal (Veri meal scores are based on glucose responses in the two hours following a meal). When you eat or drink carbohydrates, your blood sugar levels increase as your digestive system breaks the carbs down into simple sugars. Within a few hours, however, these levels should fall back to baseline (fasting) levels as your cells take in the circulating glucose from your bloodstream and turn it into energy. 

Some foods can increase your glucose levels more than others. This is especially true if they are high in refined carbohydrates and low in fiber. When you eat too much refined sugar, for example, you may experience a glucose spike — a rapid and dramatic increase in blood sugar levels, which can lead to a roller-coaster effect. So even though it’s normal for your glucose levels to increase after a meal, you still want to keep this increase gradual and smooth.

Measurements like glycemic index and glycemic load are often used to forecast the glycemic effects of different foods, but neither one can capture your biologically unique response to the things you eat. Continuous glucose monitoring is a more accurate way to understand your postprandial glucose levels and how they’re affected by food pairings, meal timing, cooking methods, etc.

What should your glucose levels be after eating?

Before sharing what research says about a healthy glucose response after eating, it’s important to know what your fasting glucose levels (i.e., glucose levels before eating) should be.

Normal fasting glucose levels = 70 and 100 mg/dL (3.9 and 5.6 mmol/L) [1]

The key is to remember that your blood sugar levels will naturally fluctuate throughout the day even if you don’t eat anything. In the hours before you wake up, for example, your glucose levels might increase to 100+ mg/dL as your liver releases stored glucose in preparation for morning activity (a.k.a., the dawn phenomenon) [2]. When do you a high-intensity exercise like HIIT, your body may release stored glucose (increasing your levels) to make sure you have enough energy to complete the workout [3].

Normal glucose levels two hours after eating = below 140 mg/dL (7.8 mmol/L) [4]

In addition to keeping your glucose levels after eating below 140 mg/dL, it’s reasonable to try to keep your postprandial glucose rise <40 mg/dL (<2.5 mmol/L), and ideally <30 mg/dL (<1.7 mmol/L). 

Why? Very preliminary research suggests that the typical postprandial glucose levels for healthy, non-diabetic people are <130 md/dL (7.2 mmol/L) [5]. In another 2009 study on 434 non-diabetic Chinese adults who wore a CGM, the reported mean fasting glucose levels were approximately 86 ± 7mg/dL, and average postprandial glucose levels 1-hour after eating were 121-123 mg/dL — which is an increase of less than 40 mg/dL [6].

Again, one-off glucose spikes aren’t always a major concern. The problem is when you regularly experience glucose levels above 140 mg/dL two hours after eating, which may be a sign you have insulin resistance.

Why are your glucose levels after eating important for metabolic health?

Your glucose levels after eating can affect your overall metabolic health in several ways.

When you experience a sudden glucose spike after eating, your pancreas releases higher-than-normal amounts of the hormone insulin to bring those levels back down. What usually follows is the feeling of a “crash,” which can leave you fatigued, shaky, and craving sugar to bring your levels up

If this happens too often, your cells become desensitized to insulin — a condition known as insulin resistance — resulting in higher-than-normal glucose levels. Insulin resistance leads to a cycle where your body stores excess glucose as fat in the liver, further disrupting healthy glucose/insulin levels and leading to weight gain. High glucose levels can also disrupt your endocrine system. For instance, they are associated with increased levels of cortisol (the stress hormone) that can further contribute to weight gain and increased inflammation throughout the body [7].

In the long run, unhealthy postprandial glucose levels can lead to serious long-term problems. One meta-analysis of 38 studies suggests that having higher postprandial glucose levels (vs. lower postprandial levels) can increase your risk of developing cardiovascular disease by up to 27% in healthy, non-diabetic individuals — even when adjusted for pre-existing CVD risk factors [8]. Another study found that higher postprandial glucose levels can increase your risk of type 2 diabetes as well [9].

How can you stabilize your postprandial glucose levels?

Diet is the most important way you can keep your postprandial glucose levels in a healthy range, but it’s not the only factor at play. Here are some tips centered around Veri’s Four Pillars of Metabolic Health:

1. Nutrition

Nutrition is the first lever to target if you’re trying to stabilize your postprandial glucose levels.

2. Exercise

Exercise can improve insulin sensitivity and glycemic control as well as reduce fasting glucose levels — preventing long-term metabolic health problems. 

  • Aim to get at least 150 minutes per week of moderate-intensity aerobic activity or 75 minutes of vigorous aerobic activity (that’s just ~20 minutes of brisk walking per day!).
  • Incorporate ~1-2 weekly resistance training sessions into your routine to increase muscle mass, which can improve insulin sensitivity and glucose management as well as help you maintain a healthy body composition.
  • Try one of our low-intensity, medium-intensity, and high-intensity weekly exercise plans for inspiration.

3. Sleep

Sleep is deeply connected to metabolic health. Consistently not getting enough sleep (less than 7-9 hours), having an irregular sleep schedule, or getting poor-quality sleep can lead to increased glucose levels, reduced glycemic control, and increased risk of insulin resistance. 

  • Maintain a consistent sleep-wake time, and try to get some sunlight within a few hours of waking up.
  • Don’t eat carbohydrates right before bed (they can disrupt your sleep).
  • Avoid having caffeine after lunch.
  • Keep your room dark with blackout curtains or a sleep mask.
  • Dim your room a few hours before bed, and avoid screens (or use night mode and a lower brightness) an hour before bed.

4. Stress

Chronic stress can increase cortisol levels, which can promote insulin resistance and higher glucose levels.

  • Practice breakwork to help you bring your stress levels (and glucose levels) down [10].
  • Spend time in nature — whether it’s the beach, a park, or even a garden — to reduce cortisol levels.
  • Tap into your social network for support during stressful times. Building a strong community in this way can actually help you increase resilience to stress and reduce your glucose levels.

5. Use a CGM

A CGM can be a powerful way to track your postprandial glucose levels and allow you to connect the dots regarding the effects of your diet, workouts, sleep schedule, and stress levels on your blood sugar. This takes the guesswork out of identifying foods and activities that support (and disrupt) a healthy glucose response, allowing you to build better habits that work with your personal biology.

Key takeaways

  • Your postprandial glucose levels are a measurement of how much glucose is circulating in your bloodstream two hours after eating or drinking.
  • Keep your glucose levels <140 mg/dL (7.8 mmol/L) two hours after eating. Aim for your postprandial glucose rise to be <40 mg/dL (<2.5 mmol/L), and ideally <30 mg/dL (<1.7 mmol/L). 
  • Chronically high postprandial glucose levels are linked to glucose intolerance, insulin resistance, cardiovascular disease, and type 2 diabetes, as well as energy dips and fatigue.
  • Diet isn’t the only way to stabilize your glucose levels after eating. Exercise regularly, practicing good sleep hygiene, and managing your stress levels are also key factors.

References:

  1. https://www.diabetes.co.uk/diabetes_care/blood-sugar-level-ranges.html
  2. https://diabetes.org/living-with-diabetes/high-morning-blood-glucose  
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3891224/ 
  4. https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/s12986-019-0368-1 
  5. https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/s12986-019-0368-1/tables/2 
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2699703/pdf/zdc1188.pdf 
  7. https://www.sciencedirect.com/science/article/abs/pii/S0306453020301177 
  8. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/217549 
  9. https://www.nature.com/articles/s41387-018-0047-8 
  10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5455070/ 

Written by: James Han
Reviewed by: Emily Johnson, MSc RD

Table of Contents

  • What are postprandial (post-meal) glucose levels?
  • What should your glucose levels be after eating?
  • Why are your glucose levels after eating important for metabolic health?
  • How can you stabilize your postprandial glucose levels?
  • Key takeaways

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