Glossary
Diabetes without the jargon: 59 terms explained in two sentences
The terms that show up on your sensor, in reports and at your appointment, explained in a sentence or two. No jargon to explain jargon: if a term needs another one to make sense, that one is here too.
Start wherever you like
14The numbers you see every dayThe terms used to measure and summarise glucose, on the sensor and in lab tests.10The sensor, decodedThe terms of the continuous sensor, Abbott's apps and the AGP report.11Every diabetes has its own storyThe types of diabetes, prediabetes and the parts of the body involved.12What you hear at the clinicThe terms of insulin, pumps and medicines for type 2 diabetes.12Eating, moving, sleepingThe terms of food, exercise, sleep and everyday situations.
This is for understanding the words. What to do with them is something to talk over with your care team, who know your case.
The numbers you see every day
- Glucose
- The sugar that circulates in the blood and that cells use for energy. It rises after eating and falls with insulin, exercise and fasting.
- Blood glucose level
- The concentration of glucose in the blood at a given moment. “Fasting glucose” is the level before eating anything, usually on waking; “postprandial glucose”, the level in the hours after a meal.
- mg/dL and mmol/L
- The two units glucose is expressed in. Spain, the United States and much of the world use milligrams per decilitre (mg/dL); the UK, Canada, Australia and others use millimoles per litre (mmol/L). To go from mmol/L to mg/dL, multiply by 18.
- Target range
- The glucose band your care team proposes as a goal. The international consensus for most adults with diabetes is 70–180 mg/dL (3.9–10 mmol/L); in pregnancy, in older or frail people and in other situations the range is different.
- Hypoglycaemia (low)
- Glucose below 70 mg/dL (3.9 mmol/L). Below 54 mg/dL (3 mmol/L) it is considered level 2 or clinically significant hypoglycaemia. It can cause shaking, sweating, hunger, confusion or dizziness, although some people feel no symptoms.
- Hyperglycaemia (high)
- Glucose above the target range; in the international consensus, above 180 mg/dL (10 mmol/L), and above 250 mg/dL (13.9 mmol/L) it is considered level 2. Sustained over time, it is what damages vessels and nerves.
- HbA1c (glycated haemoglobin)
- A blood test that estimates the average glucose of the last two or three months by measuring how much haemoglobin has glucose attached. It is expressed as a percentage (or in mmol/mol) and is the figure most used at appointments for long-term follow-up.
- GMI (glucose management indicator)
- An estimate of HbA1c from the sensor's mean glucose, with the formula 3.31 + 0.02392 × mean in mg/dL. It helps between lab tests; it does not replace lab HbA1c and can differ from it in some people.
- Mean glucose
- The average of all readings in a period. Two people with the same mean can have very different glucose: one steady and one with big rises and falls; that is why variability is also looked at.
- Glycaemic variability (CV)
- How much glucose swings around its mean. It is usually expressed as the coefficient of variation: standard deviation divided by the mean, as a percentage. The international consensus considers 36% or less stable.
- Time in range (TIR)
- The percentage of time with glucose inside the target range. The international consensus proposes, for most adults, more than 70% in 70–180 mg/dL. Each point of time in range is about 15 minutes a day.
- Time above and below range (TAR, TBR)
- The percentages of time with glucose above the range (TAR) and below it (TBR). The consensus proposes less than 25% above 180 and less than 4% below 70 (and less than 1% below 54).
- Episode
- A continuous stretch of time with glucose out of range. In GlucoBeat, a low or a high counts as an episode when it lasts at least 15 minutes without long gaps between readings.
- Sensor coverage
- The fraction of the period with sensor data. With low coverage (expired sensor, not synced, removed), the period's figures are worth less: reports usually ask for at least 70% of data over 14 days to be representative.
The sensor, decoded
- CGM (continuous glucose monitoring)
- A sensor stuck to the skin, with a thin filament under it, that measures glucose every few minutes for one or two weeks. FreeStyle Libre, Dexcom or Guardian are CGM brands.
- Interstitial glucose
- The glucose in the fluid around the cells under the skin, which is what the sensor measures. It follows blood glucose with a delay of a few minutes, longer when glucose is changing fast.
- Sensor lag
- The difference of about 5 to 15 minutes between blood glucose and interstitial glucose. It explains why, during a fast rise or fall, the sensor and a finger prick may not match.
- Capillary glucose
- The measurement from a drop of blood from the finger with a meter. It is the reference for checking the sensor when what it shows does not match how you feel.
- Trend arrow
- The arrow next to the sensor reading that says where glucose is heading and how fast. It matters as much as the number: 110 rising fast and 110 falling fast are different situations.
- FreeStyle Libre
- Abbott's CGM sensor, the most used in Spain. It is read with the phone (LibreLink app) and can be shared with family or with the clinic through LibreLinkUp and LibreView. GlucoBeat connects to LibreLinkUp and also imports the LibreView CSV.
- LibreView and LibreLinkUp
- LibreView is Abbott's platform where sensor data are stored and from which reports and the CSV are downloaded. LibreLinkUp is the app for another person (family, carer) to see the glucose of whoever wears the sensor.
- AGP (ambulatory glucose profile)
- The standard sensor report: all the days of a period overlaid on a single 24-hour day, with the median and the bands where 50% and 90% of readings fall. It shows at what times of day rises or falls repeat.
- Percentiles
- In the AGP, the lines marking the value below which a percentage of readings fall. The median (50th percentile) is the central value; the band between the 25th and 75th percentiles holds half the days; the one from the 5th to the 95th, almost all of them.
- Finger prick
- The prick on the finger to get a drop of blood. With a sensor it is still needed in some situations: when symptoms do not match the reading or when the sensor gives no value.
Every diabetes has its own story
- Type 1 diabetes
- An autoimmune disease in which the immune system destroys the beta cells of the pancreas, which produce insulin. People with it need insulin from diagnosis. It usually appears in childhood or youth, but can start at any age.
- Type 2 diabetes
- The most common form: the body responds less to insulin (insulin resistance) and over time produces less. It is linked to genetics, age, weight and physical activity, and is treated with habits, oral or injectable medication and, in some cases, insulin.
- LADA
- Latent autoimmune diabetes in adults: a slow-onset form of type 1 in adults that can be mistaken for type 2 at first. Over time it usually needs insulin.
- Gestational diabetes
- Diabetes that appears during pregnancy and usually goes away after delivery. It is watched closely because it affects the baby, and it raises the risk of developing type 2 diabetes later.
- Prediabetes
- Glucose above normal but below the diabetes threshold (for example, HbA1c between 5.7 and 6.4%). It is not a disease in itself, but it signals a high risk of type 2 diabetes that habit changes can reduce.
- MODY
- A group of rare diabetes types with a genetic cause, inherited from parent to child and appearing before the age of 25. Each type is treated differently; it is confirmed with a genetic test.
- Insulin resistance
- When cells respond less to insulin and more of it is needed for glucose to enter them. It is the central mechanism of type 2 diabetes and prediabetes.
- Beta cells
- The cells in the pancreas that make insulin. In type 1 they are destroyed by the immune system; in type 2 they wear out little by little.
- Pancreas
- An organ behind the stomach that produces insulin and glucagon, the two hormones that keep glucose in balance, as well as digestive enzymes.
- Glucagon
- The hormone that does the opposite of insulin: it tells the liver to release glucose. It also exists as an emergency medicine for severe hypoglycaemia, injected or given through the nose.
- Ketones and ketoacidosis
- Ketones are produced when the body, without enough insulin, burns fat instead of glucose. If they build up, the blood turns acidic: that is diabetic ketoacidosis, an emergency, more typical of type 1.
What you hear at the clinic
- Insulin
- The hormone that lets glucose into cells. As a medicine it is injected under the skin; there are rapid-, intermediate- and long-acting types, and mixes.
- Basal insulin
- The long-acting insulin that covers background needs through the whole day and night, regardless of meals. It is usually taken once or twice a day.
- Bolus
- A dose of rapid-acting insulin to cover a meal or to correct a high glucose. The scheme with basal plus boluses is called basal-bolus therapy.
- Insulin-to-carb ratio
- How many grams of carbohydrate one unit of rapid insulin covers in a specific person. It is worked out by the care team and varies through the day.
- Sensitivity factor (correction factor)
- How much one unit of rapid insulin lowers glucose in a specific person. It is used to calculate correction doses; the care team sets it.
- Insulin pump
- A device that delivers insulin continuously through a catheter under the skin, plus boluses on demand. With a sensor and an algorithm it forms a closed-loop or “hybrid” system.
- Closed loop (artificial pancreas)
- A system in which an algorithm adjusts the pump's insulin automatically from what the sensor reads. Today's “hybrid” systems still need the person to announce meals.
- Metformin
- The most used oral drug in type 2 diabetes: it reduces the glucose the liver produces and improves insulin sensitivity. On its own it does not usually cause lows.
- GLP-1 agonists
- Medicines (such as semaglutide or liraglutide) that mimic a gut hormone: they raise insulin when glucose rises, slow stomach emptying and reduce appetite. They are used in type 2 and in obesity.
- SGLT2 inhibitors
- Oral drugs for type 2 (such as empagliflozin or dapagliflozin) that make the kidney pass glucose into the urine. They also have protective effects on the heart and kidney.
- Sulfonylureas
- Oral drugs for type 2 (such as gliclazide) that stimulate the pancreas to release more insulin. Unlike metformin, they can cause lows.
- Rule of 15
- The guideline care teams usually teach for a mild low: take about 15 grams of fast-acting carbohydrate, wait 15 minutes and measure again. Each person follows their own team's specific instructions.
Eating, moving, sleeping
- Carbohydrates
- The nutrient that raises glucose the most: sugars, starches (bread, rice, pasta, potato, pulses) and fibre. They are counted in grams or in portions.
- Carb portion
- A unit for counting carbs: in Spain, 10 grams of carbohydrate; in other countries, 15. A slice of bread or a medium piece of fruit is roughly one or two portions.
- Glycaemic index
- A 0–100 scale that ranks foods by how fast they raise glucose compared with pure glucose. White bread has a high index; pulses, a low one. It also depends on how the food is cooked and what it is eaten with.
- Glycaemic load
- The glycaemic index multiplied by the amount of carbohydrate in the portion. It reflects a dish's real effect better: a carrot has a medium index but a low load because it has few carbs.
- Postprandial peak
- The highest value glucose reaches after a meal, usually one to two hours after starting to eat. Its height depends on what is eaten, how much, in what order and what is done afterwards.
- Dawn phenomenon
- The early-morning rise in glucose, between 3 and 8 a.m., without having eaten, caused by the hormones that prepare the body to wake up. It is common in type 1 and type 2.
- Nocturnal hypoglycaemia
- A low during sleep, sometimes without waking up. It can appear hours after intense exercise or after a dinner with alcohol; sensors with alarms help detect it.
- Effect of exercise
- Aerobic exercise (walking, running, cycling) usually lowers glucose during and after the session, sometimes hours later. Strength or very intense exercise can raise it at first because of stress hormones. Everyone responds in their own way, which is why it is worth observing.
- Alcohol and glucose
- Alcohol slows the release of glucose from the liver, so it can lower glucose hours after drinking, especially at night and on an empty stomach. Sugary drinks raise it first.
- Stress and illness
- Stress hormones (cortisol, adrenaline) and infections raise glucose and increase insulin needs. That is why sick days call for closer attention.
- Diabetes education
- The training the person with diabetes and those around them receive to understand the condition and manage daily life: what to eat, how to measure, what to do about a low. It is delivered by nursing staff and specialist educators.
- Endocrinology
- The medical specialty that treats diabetes and other hormone conditions. In primary care, type 2 follow-up is often handled by the family doctor.
Sources
- American Diabetes Association. Standards of Care in Diabetes (current edition).
- Battelino T. et al. Clinical Targets for Continuous Glucose Monitoring Data Interpretation: Recommendations From the International Consensus on Time in Range. Diabetes Care, 2019.
- Bergenstal R. M. et al. Glucose Management Indicator (GMI). Diabetes Care, 2018.
- Spanish Diabetes Society (SED).
- International Diabetes Federation (IDF). Diabetes Atlas.
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