What should my glucose levels be?

Normal blood sugar ranges for people without diabetes

Please note that blood glucose levels vary from individual to individual based on different factors such as age, sex, weight, activity levels and so on. Intense physical exercise, alongside stress, illness, medications or your menstrual cycle can also affect blood sugar levels. Also, while individual glucose readings are incredibly valuable for assessing blood sugar health, please keep in mind that trends over time are even more important for establishing a baseline. One glucose spike is unlikely to have a lasting negative impact on your health, but if you notice constant elevated levels or big spikes and crashes, that is something to address. 

Standard fasting glucose ranges

Fasting glucose is one of the most common measurements for assessing blood sugar health. The medical definition of a “fast” is a period of at least eight hours without food (e.g an overnight fast). The guidelines from the American Diabetes Association (ADA) set normal fasting glucose under 100 mg/dl. Anything above that would be considered a prediabetic or diabetic range. 

However, newer research and clinical studies assessing blood sugar levels for healthy, non-diabetic individuals show a slightly different picture on fasting glucose averages: keeping blood sugar below 90 mg/dl (ideally between 80-86 mg/dl) can have a positive impact on decreasing the risk for metabolic dysfunction. 

A note on fasting glucose: poor sleep, stress, alcohol intake, very low carb/keto diet, or a late meal the previous night are just some of the reasons why you might see elevated fasting glucose levels the next morning; keep in mind that trends over time are more telling than isolated events. If however, you constantly see elevated fasting glucose levels, have your medical provider order a fasting glucose blood draw.

Standard post-meal glucose ranges

Understanding how your body responds to various foods is also an important tool for maintaining metabolic health. The post-meal (also called postprandial) glucose measurement looks at the increase in glucose after a meal and how quickly that level drops to the pre-meal baseline in a 2-3 hour window after the meal. According to the International Diabetes Federation (IDF) guidelines, in healthy individuals without diabetes, the postprandial glucose level should not be higher than 140 mg/dl and glucose should return to pre-meal levels within 2-3 hours.

Again, standard ranges don't necessarily mean optimal ranges. According to some newer research, keeping post-meal glucose 2 hours after eating under 110 mg/dL might predict better health outcomes. Postprandial glucose levels that are too high (post-meal hyperglycemia) defined as >140 mg/dl 1-2 hours post meal can increase your risk for metabolic dysfunction. 

A note on post-meal glucose: certain foods might cause a big spike in glucose followed by an even bigger crash (when glucose levels dip below the pre-meal levels) - this is called reactive hypoglicemia and it can cause symptoms such as shakiness, diziness, headaches, fatigue, hunger, irritability, sweating and more). 

Quick cheat sheet

To keep it simple, please refer to these values for a more functional approach to optimal glucose levels that will decrease your risk for metabolic dysfunction:

  • Fasting glucose: under 90 mg/dl 
  • Mean post-meal glucose: under 140 mg/dl
  • Glucose variability: under 20 md/dl (e.g: if your pre-meal baseline is 90 mg/dl, the ideal post-meal value would be less than 110 mg/dl); good glycemic variability is linked to reduced cardiovascular risk, improved energy, and stable mood
  • Post-meal recovery: glucose should return back to pre-meal value within 2-3 hours of eating; we are looking at both how high the glucose goes and how quickly it comes back to normal - we want to avoid dramatic spikes and prolonged increases
  • Stable glucose levels throughout the day with no major spikes or crashes at least 90% of the time

Note on low glucose levels: while there is are no standard ranges for the lower treshold for healthy, nondiabetic individuals, the literature shows that  keeping  blood glucose levels above a minimum of 72 mg/dl may be beneficial. Please note that is not uncommon to notice dips in blood sugar during the night - this can be caused by a normal decrease in glucose during REM sleep or by physical pressure from sleeping on your sensor. 

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