Glossary Of Terms - G

Generic name Gland Glucosamine and Warfarin Glucose GI Glycaemic Index Low-GI
Medium-GI High-GI GI and Vitamin C GTN glyceryl trinitrate under nitrates GUCH Grown-Up Congenital Heart Disease Graft
Grip strength Glass tumbler test Glyceryl 

Generic name. The generic name eg of a drug or chemical is the general English language name. Contrast with brand name = trade name = name for a particular product manufactured and marketed by a commercial company.

About 83% (2007 figure) of NHS prescriptions by doctors in the UK are written using the generic name, so the prescribing pharmacist may provide the patient with the cheapest version of the required product. Sometimes doctors prescribe a particular brand, giving the brand name, eg if there is some reason why the patient should have that particular form of the drug.

Generic names are normally not spelt with an initial capital; but brand names normally have an initial capital.

The chemical name for a drug essentially describes its chemical composition and is normally not used by medics, pharmacists or patients.

GI stands for Glycaemic Index.

Gland. The endocrine system has various glands in different places around the body. They produce hormones and release them into the bloodstream. Each endocrine gland produces one or more hormones. Each hormone governs a particular body function. These functions include growth, repair of tissues, sexual development, reproductive functions, and response to stress.

Glucosamine is a natural body chemical that is a basic building block of several important constituents of cartilage. Our bodies can make glucosamine; and taking extra tablets or rubbing on as a gel can help to rebuild cartilage and may help to treat arthritis (explained under NSAID). As people grow older, sometimes the cartilage between the bones becomes worn – causing pain if the bones rub together as in osteoarthritis. Then glucosamine tablets or gel may relieve this pain.

Glucosamine and Warfarin

Glucosamine has been associated with an increase in the International Normalised Ratio (INR) in patients stabilised on warfarin. Although the mechanism of any interaction is unclear, patients on warfarin therapy are advised not to take (or rub in) Glucosamine. A clearer warning of this would be useful.

Patients are advised to consult their pharmacist before using over-the-counter medicines such as pain relievers; and also to discuss such other drugs with the staff of the clinic that prescribed the warfarin to ascertain if any substance may either increase or decrease warfarin’s anticlotting effect.

See interactions under Warfarin. Glucosamine should not be used on children under 12; near eyes or broken skin; nor during pregnancy.

Glucose is the type of sugar in the blood – giving energy for muscles and metabolism; and in bread, pasta, potatoes, rice, pulses, whole grains, and cereals. It is obtained from sweet foods, and from starchy foods such as bread and potatoes. After a meal the blood glucose level rises and insulin is released into the blood. When the blood glucose falls again during activity, the insulin level also falls. Insulin stops the blood glucose getting too high. Formula C6H12O6.

See Insulin and Diabetes.

Glycaemic Index, GI. Beneficial low-GI foods are digested slowly and therefore release glucose gradually into the blood. People thus feel full for longer, maintaining their energy level and metabolism, not feeling so hungry or tired, and hence feeling fewer urges to eat snacks between meals.

The GI of each food is from 0 to 100, being the rate of digesting and converting the food into glucose in the blood. Low GI is 0 to 55, medium GI 56 to 69, and high GI 70 or over.

Essentially, this means eating less sugar and foods with sugar as an ingredient; and instead having carbohydrates and other foods that are digested slowly so the body gets the energy gradually over a longer time.

Foods without any carbohydrate have zero GI – meat, poultry, fish, cheese, and eggs. Sausages have some carbohydrate so have a low GI.

Low-GI foods are beneficial: artichokes, avocado, beans (dried beans), some breads (grain bread containing whole seeds and/or nuts, rye bread, stoneground, and wholewheat bread), some breakfast cereals (having whole grains), carrots, chocolate ( plain milk and plain dark), almost all fruit and some tropical fruits (apples, apricots, blueberries, citrus fruits, gages, oranges, peaches, pears, prunes, raspberries, strawberries; but not melon, pineapple), fruit and vegetable juices, green vegetables (fresh, raw or lightly cooked), herbs, leeks, noodles, nuts, oats (stoneground and rolled oats), onions, pasta, peanuts, porridge, pulses, rice (brown, red or white; but not basmati), salad (use low-fat dressing or no dressing), seeds, yogurt.

Low GI foods 0 to 55 - some values

apple juice 40 apples 38
apricots dried 31 baked beans 48
banana 55 butter beans 31
carrots - boiled 49 cherries 22
chocolate - milk 49 crisps 54
Low-GI grapefruit 25
grapes green 46 kiwi fruit 52
lentils red 26 macaroni 45
milk skimmed 32 milk - whole milk 27
noodles 40 peanuts roasted salted 14
orange juice 46 oranges 44
Low-GI pasta 32
peaches 42 pearl barley 25
pears 38 peas 48
porridge 42 soup - lentil soup 44
soup - tomato soup 38 spaghetti - white 41
Low-GI spaghetti - wholemeal 37
sweetcorn 55 yogurt low-fat fruit 33

Medium-GI foods include: wholemeal bread, bananas, basmati rice, porridge, new potatoes, ice cream, and pineapple. Some tropical fruits are medium GI. Many medium GI foods contain useful nutrients such as vitamins and/or minerals.

Medium GI foods 56 to 69 - some values

apricots tinned 64 basmati rice 58
biscuits 59-64 bread - pitta 57
bread - rye 65 bread - wholemeal 69
coca cola 63 couscous 65
crumpet 69 croissant 67
Medium-GI honey 58
ice cream 61 melon 67
muesli 56 pineapple - fresh or tinned 66
pizza 60 potatoes boiled 56
potatoes new 62 raisins 64
shredded wheat 67 sultanas 56

High-GI foods produce glucose fast, so the person may feel hungry before the next meal is due, and if they don't use the glucose when it is produced it contributes to making them fat and overweight.

High-GI foods include: white bread, short-grain white rice, french fries, doughnuts, cornflakes, baked / mashed / jacket potatoes, many processed products (such as processed white or brown bread, white flour) and generally anything with sugar – eg sugar-rich drinks, cakes, chocolate, crisps, processed breakfast cereals (millet flakes, some mueslis, porridge, puffed wheat, rice crispies), pies, savoury and sweet pastries, croissants, and doughnuts.

However, if high-GI foods are eaten with low ones, the low-GI foods may partially slow the absorption of the sugars in the high-GI foods.

High GI foods 70 to 99 - some values

bagel 72 baguette 95
cheerios 74 chips 75
chocolate 68 cornflakes 84
french fries 75 jelly beans 80
parsnips 97 potato mashed 70, jacket 85
High-GI puffed wheat 89
rice cakes 82 rice - short-grain white 98
swedes 72 white bread 70


Research studies have shown the following, all of which are beneficial for health and/or heart risks, (though it was not clear whether each finding was statistically significant).

● Women who ate the low-GI types of carbohydrates as above had: higher HDL, lower LDL level, and lower triglycerides.

● Lower levels of homocysteine, which is an amino acid (explained under Organic chemistry), were observed in some Koreans who changed from high-GI rice to low-GI rice for six weeks. Lower levels of homocysteine reduces risk of CHD and of Alzheimer's disease.

● People who had eaten high-GI foods were found to lack calcium, iron, and zinc – which the body needs traces of. Some children who normally had high-GI diets had on average lower IQ (intelligence quotient) than those who ate a low-GI diet; but this may be because refined foods generally have reduced levels of other desirable nutrients such as the three mentioned above, and/or because of lifestyle or environment.

● Since glucose and Vitamin C are absorbed and enter cells in the same way:

 * those eating a low-GI diet had increased levels of Vitamin C absorbed from their foods.

 * if there is too much glucose, from a high-GI diet including sugar and foods containing sugar, then less Vitamin C is absorbed.

Glycerol see glycerol under Organic chemistry.

Glyceryl trinitrate. See Glyceryl trinitrate under Nitrates and glyceryl under Organic chemistry.

Glycine is a white sweet crystalline amino acid that occurs in most proteins. Also called aminoacetic acid. Formula CH2NH2COOH.

Grown-up Congenital Heart Disease GUCH describes any adult who has survived with structural or functional abnormality of the heart or blood vessels that was present at birth. A patient may or may not have had surgery to treat the condition.

Many patients have shortened life spans and therefore need specialist care. Untreated GUCH patients with even some simple conditions develop heart failure, rhythm problems and pulmonary hypertension which can significantly shorten life.

A friend was born with truncus arteriosus – a rare condition present at birth. The wall between the ventricles had not grown properly to separate the ventricles. He had a single vessel that the blood flows from the right and left sides went into. The vessel then subdivided into the pulmonary and aorta arteries. He had operations to correct the defect. He is now (2010) in his 40s, leads a completely normal life, and has a checkup once a year.

Graft. A graft is a piece of tissue, artery, vein, or organ that is transplanted to a place where it is really needed from elsewhere in the patient’s body or from a donor. It also means the operation of such transplanting and joining. See Coronary artery bypass graft.

Grip strength In a research trial reported 2010, 45% of 1572 men and 1415 women aged 59-73, their grip strengths were measured – ie how tightly they could compress a strong spring held in one hand. 45% of them were taking some cardiovascular related drug. After adjusting for age and height, those on a drug were compared with those not on a drug. Both men and women on Furosemide had reduced grip strength (both P<0.01). Those on nitrates also had reduced grip strength. Calcium channel blockers and fibrates reduced women’s but not men’s grip strength. Those on statins had no differences.

GTN See Glyceryl trinitrate under Nitrates and glyceryl under organic chemistry.

GUCH See Grown-up Congenital Heart Disease.


This information was created and edited by Richard Maddison for the BCPA.
Copyright © 1997-2019 The British Cardiac Patients Association, and/or Richard Maddison.
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First published in this form 2002, and updated 2005, 2007, 2008, 2011, 2012, 2013, 2017.
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Authors, sources and acknowledgements

The main sources are BCPA Journal published articles, other information from authors, and publicly available documents and websites. In many cases the journal articles give sources and further information than the Glossary entries.

Parts of the wordings under ECG and Echocardiogram are adapted with permission from BUPA's health information resources, available at

We hope we have thanked everyone.

Richard Maddison

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