Blood sugar control is at the center of any diabetes treatment plan. High blood sugar, or hyperglycemia, is a major concern, and can affect people with both type 1 and type 2 diabetes . There are two main
kinds: Frequent or ongoing high blood sugar can cause damage to your nerves,
blood vessels, and organs. It can also lead to other serious conditions. People with type 1 diabetes are prone to a build-up of acids in the blood called ketoacidosis. If you have
type 2 diabetes or if you’re at risk for it, extremely high blood sugar can lead to a potentially deadly condition in which your body can’t process sugar. It's called hyperglycemic hyperosmolar nonketotic syndrome (HHNS). You’ll pee more often at first, and then less often later on, but your urine may become dark and you could get severely dehydrated. It's
important to treat symptoms of high blood sugar right away to help prevent complications. Your blood sugar may rise if you: Early signs include: Ongoing high blood sugar may cause: If you have diabetes and notice any of the early signs of high blood sugar, test your blood sugar and call the doctor. They may ask you for the results of several readings. They could recommend the following changes: Drink more water. Water helps remove excess sugar from
your blood through urine, and it helps you avoid dehydration. Exercise more. Working out can help lower your blood sugar. But under certain conditions, it can make blood sugar go even higher. Ask your doctor what kind of exercise is right for you. Caution: If you have
type 1 diabetes and your blood sugar is high, you need to check your urine for ketones. When you have ketones, do NOT exercise. If you have type 2 diabetes and your blood sugar is high, you must also be sure that you have no ketones in your urine and that you are
well-hydrated. Then your doctor might give you the OK to exercise with caution as long as you feel up to it. Change your eating habits. You may need to meet with a dietitian to change the amount and types of foods you eat. Switch medications. Your doctor may change the amount, timing, or type of diabetes medications you take. Don’t make changes without talking to
them first. If you have type 1 diabetes and your blood sugar is more than 250 mg/dL, your doctor may want you to test your urine or blood for ketones. Call your doctor if your blood sugar is running higher than your treatment goals. If you work
to keep your blood sugar under control -- follow your meal plan, exercise program, and medicine schedule -- you shouldn’t have to worry about hyperglycemia. You can also: High Blood Sugar and Diabetes
Causes
Symptoms
How Is It Treated?
How to Prevent It
If someone has diabetes that isn’t treated properly, they have too much sugar in their blood (hyperglycemia). Too little sugar in the bloodstream (hypoglycemia) is usually a side effect of treatment with blood-sugar-lowering medication.
Diabetes is a metabolic disease in which there's a problem with insulin (a hormone). It can affect your health in many ways. In type 2 diabetes, not enough insulin is released into the bloodstream, or the insulin can’t be used properly. In type 1 diabetes, the body only produces very little insulin, or none at all.
When is blood sugar considered to be too high or too low?
Slight fluctuations in blood sugar levels are completely normal, and also happen every day in people who don’t have diabetes, in response to the food they eat. Between around 60 and 140 milligrams of sugar per deciliter of blood (mg/dl) is considered to be healthy. This is equivalent to a blood sugar concentration of between 3.3 and 7.8 mmol/l. “Millimoles per liter” (mmol/l) is the unit that blood sugar is measured in. It describes the amount of a certain substance per liter.
If someone has readings over 7.8 mmol/l (140 mg/dl), they are considered to have hyperglycemia. These high blood sugar levels mainly occur if there isn't enough insulin or the insulin doesn't work properly. Without the effect of insulin, the organs can't make good use of the sugar in the blood, so the sugar builds up. If type 1 diabetes is left untreated, blood sugar levels can increase to over 27.8 mmol/l (500 mg/dl). Such high levels tend to be uncommon in type 2 diabetes.
Blood sugar levels below 3.3 mmol/l (60 mg/dl) are considered to be too low. But, as you can see in the illustration below, there are no clear-cut borders between normal blood sugar levels and too high or too low blood sugar levels.
Blood sugar: Normal range between hyperglycemia and hypoglycemia
Signs of hyperglycemia
Hyperglycemia doesn't always have immediately noticeable effects. Someone might have it for years without having any physical symptoms. But very high blood sugar can cause the following symptoms:
Extreme thirst
Frequent urination
Tiredness
Listlessness
Nausea
Dizziness
If someone has extremely high blood sugar levels, they may feel confused and drowsy or even lose consciousness (diabetic coma).
What can you do if your blood sugar levels are too high?
If you have the above symptoms over a long period of time or if they keep occurring, it's important to see a doctor. They could be a sign of diabetes.
If these symptoms occur in people who have already been diagnosed with diabetes, they could be a sign that the treatment is no longer effective enough. Then medication can be prescribed or adjusted to make your blood sugar levels go back down. You may stay at the hospital while your blood sugar levels are being stabilized. If you are feeling drowsy, confused or lose consciousness, the emergency services should be called (112 in Germany and many other countries, 911 in the U.S.).
Signs of hypoglycemia
Low blood sugar is most common in people who use insulin or take certain tablets to reduce high blood sugar. This is because things like unexpected physical activity, eating too little food or drinking too much alcohol can mean that you need less insulin than you thought, causing your blood sugar to drop too low.
Signs that your blood sugar is too low may include:
Racing pulse
Cold sweats
Pale face
Headache
Feeling incredibly hungry
Shivering, feeling weak in the knees
Feeling restless, nervous or anxious
Difficulty concentrating, confusion
The severity of these symptoms depends on the blood sugar levels and can vary from person to person. The symptoms don’t occur all at once. If you aren’t sure whether your blood sugar is too low, you can measure it to make sure.
Your blood sugar levels may also drop at night, making you feel tired and weak in the morning.
Mild hypoglycemia doesn't usually have any serious health effects. But severe hypoglycemia can lead to a loss of consciousness and become life-threatening.
What can you do if your blood sugar levels are too low?
It is important to react quickly enough and eat or drink something, like dextrose sugar or a sugary drink (no "diet" or "zero" soft drinks with artificial sweeteners!).
If someone has severe hypoglycemia they may feel drowsy and confused, and might even become unconscious. People who have type 1 diabetes often carry a pre-filled syringe on them in case that happens, containing the hormone glucagon. Glucagon makes the liver release sugar into the bloodstream. Someone else can then inject the hormone if necessary. If this is not possible, it is important to call the emergency services immediately (in Germany and many other countries: 112, in the U.S.: 911) and ask for medical help.
If your blood sugar levels keep on dropping too low, you should see your doctor. It could then be a good idea to change your lifestyle or medication.
Sources
Bundesärztekammer (BÄK), Kassenärztliche Bundesvereinigung (KBV), Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF). Nationale Versorgungsleitlinie: Therapie des Typ-2-Diabetes (S3). AWMF-Registernr.: nvl-001g. December 2014.
IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.
Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.
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