RBS (Random/High blood sugar)also spelled hyperglycemia or hyperglycæmia) is a condition in which an excessive amount of glucose circulates in the blood plasma. This is generally a blood sugar level higher than 11.1 mmol/l (200 mg/dl), but symptoms may not start to become noticeable until even higher values such as 15–20 mmol/l (~250–300 mg/dl). A subject with a consistent range between ~5.6 and ~7 mmol/l (100–126 mg/dl) (American Diabetes Association guidelines) is considered slightly hyperglycemic, while above 7 mmol/l (126 mg/dl) is generally held to have diabetes. For diabetics, glucose levels that are considered to be too hyperglycemic can vary from person to person, mainly due to the person’s renal threshold of glucose and overall glucose tolerance. On average, however, chronic levels above 10–12 mmol/L (180–216 mg/dl) can produce noticeable organ damage over time.
Procedure of RBS
- A zero time (baseline) blood sample is drawn.
- The patient is then given a measured dose (below) of glucose solution to drink within a 5-minute time frame.
- Blood is drawn at intervals for measurement of glucose (blood sugar), and sometimes insulin levels. The intervals and number of samples vary according to the purpose of the test. For simple diabetes screening, the most important sample is the 2-hour sample and the 0 and 2-hour samples may be the only ones collected. A laboratory may continue to collect blood for up to 6 hours depending on the protocol requested by the physician.
The dose of glucose and variations of RBS
- 75g of an oral dose is the recommendation of the WHO to be used in all adults and is the main dosage used in the United States. The dose is adjusted for weight only in children. The dose should be drunk within 5 minutes.
- A variant is often used in pregnancy to screen for gestational diabetes, with a screening test of 50 grams over one hour. If elevated, this is followed by a test of 100 grams over three hours.
- In UK general practice, the standard glucose load was provided by 394ml of the energy drink Lucozade with original carbonated flavor, but this is being superseded by purpose-made drinks.
- In Portugal, the standard glucose load is provided by the clinical laboratory or hospital by 200 ml of fluid in a PET bottle. The best-known brand is TopStar, produced in Portugal. The recommendation is for a 75g oral dose for all adults, which is adjusted for weight in children. However, doses of 50g and 100g are also used, available in orange, lemon and cola flavor.
Substances measured and variations of RBS
If renal glycosuria (sugar excreted in the urine despite normal levels in the blood) is suspected, urine samples may also be collected for testing along with the fasting and 2-hour blood tests.
Results of RBS
- Fasting plasma glucose (measured before the OGTT begins) should be below 6.1 mmol/L (110 mg/dL). Fasting levels between 6.1 and 7.0 mmol/L (110 and 125 mg/dL) are borderline (“impaired fasting glycaemia”), and fasting levels repeatedly at or above 7.0 mmol/L (>126 mg/dL) are diagnostic of diabetes.
- A 1-hour GTT (Glucose Tolerance Test) glucose level below 10 mmol/L (180 mg/dL) is considered normal.
- For a 2 hour GTT (Glucose Tolerance Test) with 75g intake, a glucose level below 7.8 mmol/L (140 mg/dL) is normal, whereas higher glucose levels indicate hyperglycemia. Blood plasma glucose between 7.8 mmol/L (140 mg/dL) and 11.1 mmol/L (200 mg/dL) indicate “impaired glucose tolerance”, and levels above 11.1 mmol/L (200 mg/dL) at 2 hours confirm a diagnosis of diabetes.
For gestational diabetes, the American College of Obstetricians and Gynecologists (ACOG) recommends a two-step procedure, wherein the first step is a 50g glucose dose. If it results in a blood glucose level of more than 7.8 mmol/L (140 mg/dL), it is followed by a 100-gram glucose dose. The diagnosis of gestational diabetes is then defined by a blood glucose level exceeding the cutoff value on at least two intervals, with cutoffs as follows
- Before glucose intake (fasting): 5.3 mmol/L (95 mg/dL)
- 1 hour after drinking the glucose solution: 10 mmol/L (180 mg/dL)
- 2 hours: 8.6 mmol/L (155 mg/dL)
- 3 hours: 7.8 mmol/L (140 mg/dL)
| Target Levels by Type |
Upon waking | Before meals (preprandial) |
At least 90 minutes after meals (postprandial) |
|---|---|---|---|
| Non-diabetic* | 4.0 to 5.9 mmol/L | under 7.8 mmol/L | |
| Type 2 diabetes | 4 to 7 mmol/L | under 8.5 mmol/L | |
| Type 1 diabetes | 5 to 7 mmol/L | 4 to 7 mmol/L | 5 to 9 mmol/L |
| Children w/ type 1 diabetes | 4 to 7 mmol/L | 4 to 7 mmol/L | 5 to 9 mmol/L |
*The non-diabetic figures are provided for information but are not part of NICE guidelines.
Normal and diabetic blood sugar ranges
For the majority of healthy individuals, normal blood sugar levels are as follows:
- Between 4.0 to 6.0 mmol/L (72 to 108 mg/dL) when fasting
- Up to 7.8 mmol/L (140 mg/dL) 2 hours after eating
For people with diabetes, blood sugar level targets are as follows:
- Before meals: 4 to 7 mmol/L for people with type 1 or type 2 diabetes
- After meals: under 9 mmol/L for people with type 1 diabetes and under 8.5mmol/L for people with type 2 diabetes
Blood sugar levels in diagnosing diabetes
The following table lays out criteria for diagnoses of diabetes and prediabetes.
| Plasma glucose test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Random | Below 11.1 mmol/l Below 200 mg/dl |
N/A | 11.1 mmol/l or more 200 mg/dl or more |
| Fasting | Below 6.1 mmol/l Below 108 mg/dl |
6.1 to 6.9 mmol/l 108 to 125 mg/dl |
7.0 mmol/l or more 126 mg/dl or more |
| 2 hour post-prandial | Below 7.8 mmol/l Below 140 mg/dl |
7.8 to 11.0 mmol/l 140 to 199 mg/dl |
11.1 mmol/l or more 200 mg/dl or more |
Causes of Random/high Blood Suger
Sometimes, hyperglycemia is not the result of diabetes. Other medical conditions that can cause hyperglycemia include:
- Pancreatitis (inflammation of the pancreas)
- Pancreatic cancer
- Hyperthyroidism (overactive thyroid gland)
- Cushing’s syndrome (elevated blood cortisol level)
- Unusual tumors that secrete hormones, including glucagonoma, pheochromocytoma, or growth hormone-secreting tumors
- Severe stresses on the body, such as heart attack, stroke, trauma, or severe illnesses, can temporarily lead to hyperglycemia
- Taking certain medications, including prednisone, estrogens, beta-blockers, glucagon, oral contraceptives, phenothiazines, and others, can elevate blood glucose levels
| Persistent hyperglycemia | Transient hyperglycemia | Persistent hypoglycemia | Transient hypoglycemia |
|---|---|---|---|
| Reference range, FBG: 70–110 mg/dL | |||
| Diabetes mellitus | Pheochromocytoma | Insulinoma | Acute alcohol ingestion |
| Adrenal cortical hyperactivity Cushing’s syndrome | Severe liver disease | Adrenal cortical insufficiency Addison’s disease | Drugs: salicylates, antituberculosis agents |
| Hyperthyroidism | Acute stress reaction | Hypopituitarism | Severe liver disease |
| Acromegaly | Shock | Galactosemia | Several glycogen storage diseases |
| Obesity | Convulsions | Ectopic insulin production from tumors | Hereditary fructose intolerance |
High Blood Sugar Symptoms
Common symptoms can include:
- Dry mouth
- Thirst
- Frequent urination
- Urination during the night
- Skin rash
- Fatigue or drowsiness
- Increased appetite
- Polyphagia – frequent hunger, especially pronounced hunger
- Polydipsia – frequent thirst, especially excessive thirst
- Polyuria – increased volume of urination (not an increased frequency for urination)
- Restlessness
- Weight loss
- Poor wound healing (cuts, scrapes, etc.)
- Tingling in feet or heels
- Erectile dysfunction
- Recurrent infections, external ear infections (swimmer’s ear)
- Cardiac arrhythmia
- Stupor
- Coma
- Seizures
- Difficulty breathing
- Dizziness upon standing
- Rapid weight loss
- Increased drowsiness and confusion
- Unconsciousness or coma
Treatment of RBS
Management of type 2 diabetes includes:
- Healthy eating
- Regular exercise
- Possibly, diabetes medication or insulin therapy
- Blood sugar monitoring
Healthy eating
Contrary to popular perception, there’s no specific diabetes diet. However, it’s important to center your diet on these high-fiber, low-fat foods:
- Fruits
- Vegetables
- Whole grains
- You’ll also need to eat fewer animal products, refined carbohydrates and sweets.
Physical activity
- Everyone needs regular aerobic exercise, and people who have type 2 diabetes are no exception. Get your doctor’s OK before you start an exercise program. Then choose activities you enjoy, such as walking, swimming and biking. What’s most important is making physical activity part of your daily routine.
- Aim for at least 30 minutes of aerobic exercise five days of the week. Stretching and strength training exercises are important, too. If you haven’t been active for a while, start slowly and build up gradually.
A combination of exercises
- Aerobic exercises, such as walking or dancing on most days, combined with resistance training, such as weightlifting or yoga twice a week — often helps control blood sugar more effectively than either type of exercise alone.
Monitoring your blood sugar
- Depending on your treatment plan, you may need to check and record your blood sugar level every now and then or, if you’re on insulin, multiple times a day. Ask your doctor how often he or she wants you to check your blood sugar. Careful monitoring is the only way to make sure that your blood sugar level remains within your target range.
Diabetes medications and insulin therapy
- Some people who have type 2 diabetes can achieve their target blood sugar levels with diet and exercise alone, but many also need diabetes medications or insulin therapy. The decision about which medications are best depends on many factors, including your blood sugar level and any other health problems you have. Your doctor might even combine drugs from different classes to help you control your blood sugar in several different ways.
Examples of possible treatments for type 2 diabetes include
Metformin (Glucophage, Glumetza, others)
- Generally, metformin is the first medication prescribed for type 2 diabetes. It works by improving the sensitivity of your body tissues to insulin so that your body uses insulin more effectively.
- Metformin also lowers glucose production in the liver. Metformin may not lower blood sugar enough on its own. Your doctor will also recommend lifestyle changes, such as losing weight and becoming more active.
Sulfonylureas
- These medications help your body secrete more insulin. Examples of medications in this class include glyburide, glipizide, and glimepiride. Possible side effects include low blood sugar and weight gain.
Meglitinides
- These medications work like sulfonylureas by stimulating the pancreas to secrete more insulin, but they’re faster acting, and the duration of their effect in the body is shorter. They also have a risk of causing low blood sugar, but this risk is lower than with sulfonylureas.
Thiazolidinediones
- Like metformin, these medications make the body’s tissues more sensitive to insulin. This class of medications has been linked to weight gain and other more-serious side effects, such as an increased risk of heart failure and fractures. Because of these risks, these medications generally aren’t a first-choice treatment.
DPP-4 inhibitors
- These medications help reduce blood sugar levels, but tend to have a modest effect. They don’t cause weight gain. Examples of these medications are sitagliptin , saxagliptin and linagliptin .
GLP-1 receptor agonists
- These medications slow digestion and help lower blood sugar levels, though not as much as sulfonylureas. Their use is often associated with some weight loss. This class of medications isn’t recommended for use by itself
SGLT2 inhibitors
- These are the newest diabetes drugs on the market. They work by preventing the kidneys from reabsorbing sugar into the blood. Instead, the sugar is excreted in the urine.
Insulin therapy
- Some people who have type 2 diabetes need insulin therapy as well. In the past, insulin therapy was used as a last resort, but today it’s often prescribed sooner because of its benefits.
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