This blog was originally published in 2023 and updated in September 2026 to reflect current information and improve accuracy.
Blood sugar levels naturally rise and fall throughout the day, but readings that become too high or too low can affect how you feel and, in some cases, require immediate attention.
For many nonpregnant adults with diabetes, a typical blood sugar goal is 80–130 mg/dL before a meal and less than 180 mg/dL one to two hours after the start of a meal. These targets are not the same for everyone. Your age, medications, overall health, and risk of low blood sugar can all affect the range your healthcare provider recommends.
Knowing your personal target range, recognizing symptoms, and having a plan for unexpected highs and lows are important parts of managing diabetes.
For many nonpregnant adults with diabetes, the general target is 80–130 mg/dL before meals and less than 180 mg/dL one to two hours after eating.
Your individual targets may be different. A primary care provider can consider your health history, medications, age, and other factors when setting appropriate goals.
Blood sugar readings also provide more useful information when viewed as a pattern rather than as isolated numbers. Regular monitoring can show whether glucose tends to rise or fall at certain times of day, after particular meals, during exercise, or after taking medication.
Periodic laboratory testing, including A1C testing when recommended, can provide a broader picture of blood sugar control over time.
Blood sugar below 70 mg/dL is considered low and should be treated promptly. A reading below 54 mg/dL is considered level 2 hypoglycemia and requires immediate action.
Low blood sugar may cause:
Hypoglycemia can occur when the body has more insulin or glucose-lowering medication than it needs. Skipping or delaying a meal, exercising more than usual, drinking alcohol, or changes in medication can also contribute.
Severe hypoglycemia can lead to seizures, loss of consciousness, or the need for another person to provide assistance. Frequent lows or episodes that occur without noticeable symptoms should be discussed with your healthcare provider.
For many people, you can treat low blood sugar using the 15-15 rule: eat 15 grams of fast-acting carbohydrate, wait 15 minutes, and check your blood sugar again.
If your glucose is still below 70 mg/dL, repeat the process until it returns to your target range. Examples of fast-acting carbohydrates include glucose tablets, glucose gel, 4 ounces of juice or regular soda, or 1 tablespoon of sugar or honey.
Once your glucose has returned to your target range, follow your individual diabetes plan. Your healthcare provider may give you different instructions based on your medications, insulin delivery system, age, or history of hypoglycemia.
Blood sugar above your individual target range is considered high. For many nonpregnant adults with diabetes, a reading above 180 mg/dL one to two hours after the start of a meal is above the typical postmeal goal.
High blood sugar may cause:
Illness, stress, eating more carbohydrates than usual, missed medication, or not having enough insulin can all contribute to high blood sugar.
A single reading above your target does not necessarily mean there is an emergency. However, very high blood sugar can become serious when ketones build up in the body and lead to diabetic ketoacidosis, or DKA, which requires urgent medical treatment.
If your blood sugar is above your target, follow the treatment plan provided by your healthcare team rather than making major medication or insulin changes on your own.
Depending on your plan, this may involve checking your glucose again, drinking water, taking medication or correction insulin as prescribed, and considering what may have caused the change.
Exercise can sometimes lower blood sugar, but it is not always appropriate when glucose is very high. The American Diabetes Association advises checking for ketones when glucose is above 240 mg/dL before exercising. If ketones are present, exercise can raise glucose further.
If highs happen frequently, your provider may need to review your eating patterns, activity, medication, or insulin plan. Diabetes management can help patients build a plan around glucose monitoring and everyday habits.
Blood sugar can rise or fall because of changes in food, activity, illness, stress, or diabetes medications.
Eating more carbohydrates than usual, illness, stress, or not having enough insulin can raise blood sugar. Skipping meals, taking certain medications, drinking alcohol, or being more active than expected can cause it to drop.
Looking for patterns can help prevent repeated highs and lows. Helpful habits include checking blood sugar as recommended, taking medications as directed, eating consistently, staying active, and keeping fast-acting carbohydrates available for low blood sugar.
Practical strategies for managing life with diabetes can also help with day-to-day glucose control. Because food choices and meal timing affect blood sugar, nutrition support may help patients better understand carbohydrates, portions, and eating patterns.
If your readings frequently fall outside your target range, talk with your healthcare provider. Repeated highs or lows may mean your diabetes plan needs to be adjusted.
High or low blood sugar becomes an emergency when the person cannot safely treat the problem at home or develops severe symptoms.
Call 911 for severe low blood sugar if the person is unconscious, having a seizure, unable to swallow safely, or unable to treat themselves.
Very high blood sugar can also require emergency care when signs of DKA develop. Warning signs can include vomiting, difficulty breathing, confusion, fruity-smelling breath, severe fatigue, or an inability to keep fluids down. The CDC also advises emergency evaluation when blood sugar remains at 300 mg/dL or higher or when multiple signs of DKA are present.
If you have been prescribed glucagon for severe hypoglycemia or have a ketone-monitoring plan, make sure family members or caregivers understand when and how those tools should be used.
Talk with your healthcare provider if you are experiencing repeated high or low readings, new symptoms, difficulty reaching your target range, or changes in your eating habits, activity, medications, or overall health.
You should also speak with your provider if you are not sure what your personal glucose targets should be or what steps to take when a reading falls outside that range.
At Lane Regional Medical Center, patients in Zachary can access care and support for diabetes and related health needs. If you are having difficulty managing your blood sugar or need help developing an individualized plan, you can request an appointment.
This blog was written by Maria North-Scott, D.O., a board-certified family medicine physician at Lane Family Practice. Dr. North-Scott is board certified in Family Medicine, Osteopathic Manipulation Therapy, and Obesity Medicine and provides care for adults and children, including preventive care, diabetes management, blood pressure management, annual wellness exams, and other primary care needs.