A blood sugar of 78 mg/dL is not low. It falls squarely within the normal range for healthy adults, whether taken fasting or at any other time of day. Normal fasting blood sugar is anything below 100 mg/dL, and most healthy people hover between 70 and 99 mg/dL throughout the day. At 78, your body is doing exactly what it should be doing.
Where 78 Fits in the Normal Range
The standard cutoff for normal fasting blood sugar is below 100 mg/dL. Readings between 100 and 125 mg/dL are considered prediabetic, and 126 mg/dL or higher on two separate tests indicates diabetes. At 78, you’re well below any of those thresholds.
If you’re checking after a meal, 78 mg/dL is also perfectly fine. Post-meal blood sugar in healthy people typically stays below 140 mg/dL, so seeing 78 two or more hours after eating simply means your body processed the glucose efficiently. Some people see numbers in the 70s or low 80s between meals as a matter of routine.
When Blood Sugar Is Actually Considered Low
Hypoglycemia, the medical term for low blood sugar, is generally defined as a reading below 70 mg/dL. That’s the threshold where most people start to feel symptoms: shakiness, sweating, irritability, dizziness, or a sudden sense of hunger. Below 54 mg/dL is considered seriously low and requires immediate treatment with fast-acting sugar.
At 78, you have a comfortable 8-point buffer above that 70 mg/dL line. Your pancreas has a built-in system for preventing drops below that level. When blood sugar starts trending downward, your pancreas releases glucagon, a hormone that signals your liver to break down its stored glucose and release it into your bloodstream. This process kicks in automatically and keeps most healthy people from ever dipping into true hypoglycemia.
Why 78 Might Feel Low
Some people see 78 on their meter and feel off, even though the number is normal. This usually happens for one of two reasons.
First, if your blood sugar has been running high for a while (in the 150s, 200s, or higher), your body adjusts to that elevated baseline. When levels drop back into the normal range, your brain interprets the change as a problem even though 78 is objectively healthy. This is sometimes called “relative hypoglycemia.” The symptoms are real, but they fade over days or weeks as your body readjusts to normal glucose levels.
Second, timing matters. If you checked right after exercise, or several hours into a fast, you might catch your blood sugar at the lower end of normal and happen to feel hungry or tired for unrelated reasons. It’s easy to attribute those feelings to the number on the screen.
What 78 Means if You Have Diabetes
For people managing type 1 or type 2 diabetes, the CDC recommends a pre-meal target of 80 to 130 mg/dL. A reading of 78 sits just below that range, which is worth paying attention to but not alarming. If you’re on insulin or medications that actively lower blood sugar, a reading of 78 before a meal could mean you’re trending downward and might want to have a small snack, especially if your next meal is more than an hour away.
The concern for people on blood sugar-lowering medication isn’t the 78 itself. It’s the trajectory. If you were 110 an hour ago and now you’re 78, you’re dropping relatively quickly, and continuing that trend could push you below 70. Continuous glucose monitors make this easier to spot because they show direction and speed of change, not just a single snapshot. If you’re only using a fingerstick meter, checking again in 15 to 20 minutes can tell you whether you’re stable or still falling.
What 78 Means During Pregnancy
Pregnant women with diabetes (or gestational diabetes) have slightly different targets. The American College of Obstetricians and Gynecologists recommends a fasting blood sugar below 95 mg/dL during pregnancy. A reading of 78 falls comfortably within that goal. Blood sugar naturally fluctuates more during pregnancy due to hormonal shifts, so seeing occasional readings in the mid-to-upper 70s is expected and healthy.
The Bottom Line on 78 mg/dL
For the vast majority of people, 78 mg/dL is a completely normal blood sugar reading. It is not hypoglycemia. If you feel symptoms like shakiness or lightheadedness at this level, the likely explanation is that your body has been accustomed to higher numbers and needs time to recalibrate. If you take insulin or other glucose-lowering medications and consistently see readings in the upper 70s before meals, it’s worth mentioning at your next appointment to see whether a dosage adjustment makes sense.