What Should You Do to Start Managing Blood Sugar Effectively?
Begin by working with your healthcare team to set personalized glucose targets. Learn your numbers: target A1C, fasting glucose range, and postmeal glucose goals. Start a monitoring routine using a blood glucose meter or continuous glucose monitor. Track how food, activity, stress, and medications affect your levels. Small consistent changes produce better long-term results than dramatic overhauls.
Effective blood sugar management starts with knowing your targets and measuring against them consistently. The ADA Standards of Care 2025 recommend an A1C below 7 percent for most non-pregnant adults, corresponding to an estimated average glucose of approximately 154 mg/dL. Pre-meal (fasting) glucose targets are 80 to 130 mg/dL, and postprandial (after-meal) targets are below 180 mg/dL measured 1 to 2 hours after the start of a meal. These targets may be individualized: more stringent (A1C below 6.5 percent) for younger patients with short diabetes duration and no significant cardiovascular disease, or less stringent (A1C below 8 percent) for older adults with limited life expectancy, extensive comorbidities, or high hypoglycemia risk.
Building a monitoring routine is essential. Whether using finger-stick testing or continuous glucose monitoring, consistent data collection reveals patterns that guide treatment decisions. Keep a log of blood sugar readings alongside notes about meals, activity, stress, sleep, and medications. Many glucose meters and CGM apps generate reports and graphs that make patterns visible. Share these reports with your healthcare team at every visit. The ADA recommends that people with diabetes who are not meeting glycemic goals or who have changed therapy be seen at least quarterly until targets are achieved.
The ADA Standards of Care 2025 recommend an A1C below 7 percent for most non-pregnant adults with pre-meal glucose targets of 80 to 130 mg/dL
What Are the Blood Sugar Targets for People With Diabetes?
The ADA recommends the following glycemic targets for most non-pregnant adults with diabetes: A1C below 7 percent, fasting and pre-meal glucose 80 to 130 mg/dL, postprandial glucose below 180 mg/dL, and time in range of 70 percent or more. Targets should be individualized based on patient factors including age, comorbidities, and hypoglycemia risk.
A1C reflects average blood glucose over approximately 2 to 3 months by measuring the percentage of hemoglobin that has glucose attached to it. An A1C of 7 percent corresponds to an estimated average glucose of about 154 mg/dL. The relationship between A1C and complications was established by the DCCT and UKPDS trials, which showed that each 1 percent reduction in A1C reduces microvascular complications by approximately 37 percent. However, A1C has limitations: it does not capture glucose variability and can be unreliable in conditions affecting red blood cell turnover, including hemoglobin variants, iron deficiency, pregnancy, and chronic kidney disease.
Time in range has emerged as an important complementary metric, particularly with the widespread adoption of continuous glucose monitoring. The international consensus on CGM metrics recommends that most adults with type 1 or type 2 diabetes aim for TIR above 70 percent (glucose 70 to 180 mg/dL for at least 16 hours and 48 minutes per day), with time below range below 4 percent (less than 1 hour per day below 70 mg/dL) and less than 1 percent (less than 15 minutes per day below 54 mg/dL). Research published in Diabetes Care has demonstrated that each 10 percentage point increase in TIR is associated with a 64 percent lower risk of retinopathy progression.
The UKPDS showed that each 1 percent reduction in A1C reduces microvascular complications by approximately 37 percent
How Do Continuous Glucose Monitors Work?
CGMs use a small sensor inserted under the skin to measure glucose in interstitial fluid every 1 to 5 minutes. They wirelessly transmit readings to a smartphone or receiver, providing real-time glucose values, trend arrows showing direction and speed of change, and customizable high and low alerts. CGMs have been shown to improve A1C and reduce hypoglycemia.
Current CGM systems include the Dexcom G7 (readings every 5 minutes, 10-day sensor wear), FreeStyle Libre 3 (readings every minute, 14-day sensor), and Medtronic Guardian 4 (paired with insulin pumps for automated insulin delivery). Sensors are typically inserted on the back of the upper arm or abdomen using a spring-loaded applicator. The sensor contains a tiny electrode coated with glucose oxidase enzyme, which generates an electrical signal proportional to the glucose concentration in the interstitial fluid. This signal is calibrated and converted to a glucose reading displayed on the user's device.
The key advantages of CGM over traditional finger-stick testing include visibility of glucose trends and direction (is glucose rising, falling, or stable?), high and low glucose alerts that warn before dangerous levels are reached, overnight monitoring without waking up, and comprehensive data capture enabling reports on time in range, glucose variability, and patterns. A pivotal study published in JAMA showed that CGM use in adults with type 2 diabetes on basal insulin reduced A1C by 0.4 percentage points compared to traditional monitoring, with significantly improved time in range. The ADA now recommends CGM for all people with diabetes on insulin therapy and considers it beneficial for those on other glucose-lowering therapies as well.
A JAMA study showed CGM use in adults with type 2 diabetes on basal insulin reduced A1C by 0.4 percentage points with improved time in range
How Does Food Affect Blood Sugar Levels?
Carbohydrates have the greatest direct impact on blood sugar, with most carbohydrate foods causing glucose to peak 1 to 2 hours after eating. Protein and fat have minimal direct glucose impact but slow carbohydrate absorption. Meal composition, portion size, glycemic index, fiber content, and food order all influence the postprandial glucose response.
Understanding the glycemic impact of different foods is fundamental to blood sugar management. Carbohydrates are broken down into glucose during digestion, directly raising blood sugar. Refined carbohydrates with high glycemic index (white bread, white rice, sugary drinks, candy) cause rapid glucose spikes, while complex carbohydrates with low glycemic index (whole grains, legumes, most vegetables and fruits) produce more gradual rises. Fiber, particularly soluble fiber found in oats, beans, and certain fruits, slows glucose absorption and reduces postprandial spikes. The ADA recommends that adults with diabetes consume at least 14 grams of fiber per 1,000 calories.
Emerging research supports the concept of food order or meal sequencing for glucose management. A study published in Diabetes Care found that eating protein and vegetables before carbohydrates reduced postprandial glucose by 29 percent and insulin levels by 37 percent compared to eating carbohydrates first. Similarly, adding vinegar (1 to 2 tablespoons) to meals has been shown to reduce postprandial glucose by 20 to 30 percent in several studies. Portion control using the diabetes plate method — half plate non-starchy vegetables, one quarter lean protein, one quarter complex carbohydrates — provides a practical framework that does not require calorie or carbohydrate counting.
How Does Exercise Affect Blood Sugar?
Exercise improves blood sugar in multiple ways: muscles take up glucose during activity independently of insulin, insulin sensitivity improves for 24 to 72 hours after exercise, and regular activity reduces A1C by 0.5 to 0.7 percentage points. Both aerobic and resistance exercise are beneficial. The ADA recommends 150 minutes per week of moderate-intensity activity.
During aerobic exercise, working muscles increase glucose uptake by 7 to 20 fold through insulin-independent mechanisms. Muscle contractions activate GLUT4 glucose transporters that move glucose from the blood into muscle cells without needing insulin. This acute glucose-lowering effect continues after exercise ends through enhanced insulin sensitivity, as muscle glycogen stores are replenished. The effect lasts 24 to 72 hours, which is why the ADA recommends no more than 2 consecutive days without physical activity. A brisk 15-minute walk after meals can reduce postprandial glucose peaks by 22 percent, according to research published in Diabetes Care.
Resistance training provides complementary benefits by increasing muscle mass, which is the body's primary site for insulin-stimulated glucose disposal. Greater muscle mass means more glucose uptake capacity. A meta-analysis in Sports Medicine found that resistance training alone reduces A1C by an average of 0.34 percentage points, while combined aerobic and resistance training produces the greatest improvements. For people on insulin or sulfonylureas, exercise requires careful planning to avoid hypoglycemia — blood sugar should be checked before, during (for exercise lasting more than 1 hour), and after activity, with carbohydrate intake or insulin adjustments as needed.
Research in Diabetes Care showed that a 15-minute post-meal walk reduces postprandial glucose peaks by 22 percent
How Do Medications Affect Blood Sugar Management?
Different diabetes medications work through distinct mechanisms and have varying effects on blood sugar patterns. Metformin reduces liver glucose output and improves insulin sensitivity. GLP-1 receptor agonists slow gastric emptying and enhance insulin secretion. SGLT2 inhibitors block kidney glucose reabsorption. Understanding your medications helps optimize timing and effectiveness.
Metformin, the most widely prescribed diabetes medication, primarily reduces hepatic glucose production and improves insulin sensitivity in muscle and fat tissue. It does not cause hypoglycemia when used alone and is weight-neutral. For optimal effectiveness, take metformin with meals to reduce gastrointestinal side effects. Extended-release metformin is taken once daily and causes fewer GI symptoms. GLP-1 receptor agonists like semaglutide (Ozempic, weekly injection) and liraglutide (Victoza, daily injection) enhance meal-stimulated insulin secretion, suppress inappropriate glucagon secretion, slow gastric emptying (reducing postprandial spikes), and reduce appetite leading to weight loss.
SGLT2 inhibitors including empagliflozin (Jardiance) and dapagliflozin (Farxiga) work independently of insulin by blocking glucose reabsorption in the kidneys, causing excess glucose to be excreted in the urine. This mechanism provides glucose lowering regardless of beta cell function or insulin resistance severity. Sulfonylureas (glipizide, glimepiride) stimulate insulin secretion and can cause hypoglycemia, particularly in older adults or those with irregular eating patterns. DPP-4 inhibitors (sitagliptin, saxagliptin) enhance the body's own incretin hormones and are well-tolerated with low hypoglycemia risk. The ADA recommends medication timing aligned with meals and consistent daily routines for optimal glucose control.
What Factors Cause Unexpected Blood Sugar Fluctuations?
Beyond food and exercise, many factors affect blood sugar. Stress, illness, hormonal changes, sleep quality, dehydration, certain medications, alcohol, and even weather can cause unexpected glucose fluctuations. Understanding these factors helps you anticipate and manage blood sugar changes proactively.
Physical and emotional stress activate the hypothalamic-pituitary-adrenal axis, releasing cortisol and adrenaline that promote liver glucose output and increase insulin resistance. Acute illness, infection, or surgery can raise blood sugar dramatically, sometimes requiring temporary insulin use even in people normally managed with oral medications. The ADA recommends sick-day management plans that include more frequent blood sugar monitoring (every 2 to 4 hours), checking for ketones if glucose exceeds 240 mg/dL, maintaining hydration, and never stopping insulin during illness. Hormonal fluctuations during menstrual cycles, pregnancy, puberty, and menopause can also cause glucose variability.
Sleep quality significantly influences blood sugar control. Research published in Diabetes Care shows that sleeping fewer than 6 hours or more than 9 hours per night is associated with higher A1C levels. Sleep deprivation increases cortisol, reduces insulin sensitivity, and impairs glucose tolerance. Obstructive sleep apnea, which is common in people with type 2 diabetes, further worsens glycemic control. Dehydration concentrates blood glucose, making readings appear higher. Alcohol can cause both hyperglycemia (from sugar content in drinks) and delayed hypoglycemia (from impaired liver glucose production), making blood sugar monitoring essential when drinking. Certain medications including corticosteroids, beta-blockers, thiazide diuretics, and some antipsychotics can significantly raise blood sugar.
- Stress and illness: raise blood sugar through cortisol and counter-regulatory hormones
- Sleep deprivation: reduces insulin sensitivity and increases cortisol
- Dehydration: concentrates blood glucose and impairs kidney function
- Alcohol: causes delayed hypoglycemia risk, especially with insulin
- Medications: corticosteroids, beta-blockers, and some antipsychotics raise blood sugar
- Hormonal changes: menstrual cycle, pregnancy, menopause affect glucose levels
- Dawn phenomenon: early morning liver glucose release raises fasting blood sugar
- Weather and temperature: extreme heat increases insulin absorption rate
How Can You Prevent and Treat Hypoglycemia?
Prevent hypoglycemia by eating regular meals, timing medications correctly, adjusting insulin for exercise, and monitoring blood sugar before driving and sleeping. Treat mild hypoglycemia with the rule of 15: consume 15 grams of fast-acting carbs, wait 15 minutes, recheck. For severe hypoglycemia with loss of consciousness, use glucagon and call 911.
Hypoglycemia prevention requires matching insulin and medication doses to food intake and activity levels. Meal skipping or delayed meals are common causes of hypoglycemia in people on insulin or sulfonylureas. The ADA recommends checking blood sugar before driving (and not driving if below 90 mg/dL), before exercise, and at bedtime. Nocturnal hypoglycemia is particularly dangerous because warning symptoms may not wake the person. A bedtime blood sugar of 100 to 140 mg/dL is generally safe; if below 100 mg/dL, a small snack containing protein and carbohydrate may prevent overnight lows. CGMs with low glucose alerts provide an important safety net during sleep.
Treating mild to moderate hypoglycemia (blood sugar 54 to 70 mg/dL) follows the rule of 15: consume 15 grams of fast-acting glucose (4 glucose tablets, 4 ounces of juice or regular soda, or 1 tablespoon of honey or sugar), wait 15 minutes, recheck blood sugar, and repeat if still below 70 mg/dL. Once blood sugar normalizes, eat a meal or snack to prevent recurrence. Severe hypoglycemia (below 54 mg/dL with impaired consciousness or inability to self-treat) requires someone else to administer glucagon. Nasal glucagon (Baqsimi) and pre-filled glucagon injection pens (Gvoke HypoPen) are easy for bystanders to use. Always call 911 for severe hypoglycemia.
The ADA recommends the rule of 15 for treating hypoglycemia: 15 grams of fast-acting carbohydrate, wait 15 minutes, and recheck blood sugar
