Normal temperature is usually around 37 °C (98,6 °F). However, normal temperature is not the same for every individual. Temperature can vary with age, and even time of day. Usually it is lowest in the morning, highest in the afternoon and somewhat lower at bedtime.

It is of great medical importance to measure body temperature. The reason is that a number of diseases are accompanied by characteristic changes in body temperature. Likewise, the course of certain diseases can be monitored by measuring body temperature, and the efficiency of a treatment initiated can be evaluated by the physician. Fever is a reaction to disease-specific stimuli, where the set point of the temperature control centre is varied to promote the body's defenses against the disease process. Fever is the most common form of pathological (disease- related) elevation on body temperature.

Essentially a distinction must be made between the technical accuracy of the thermometer itself and the clinical accuracy in use in taking a temperature. The former is determined under idealized conditions to guarantee the quality of the instrument, taking the relevant technical standards into account. An accuracy of +/- 0.1°C can be considered state of the art for high-grade thermometers. The user must not confuse technical accuracy with this accuracy in use. The human body temperatures described here, which depend on the measurement location and time, are due to physiological causes and are not due to a thermometer malfunction.

Rectal - The most reliable core temperature is obtained by inserting a thermometer into the rectum (rectal measurement). This measurement is accurate and has low scattering in the results. The normal range is approximately: 36.2°C - 37.7°C.

Vaginal - In women, vaginal temperature measurement yields a slight underestimate of temperature by an average of 0.1°C to 0.3°C in comparison with a rectal measurement with comparable stability.

Ear - Ear thermometers measure the temperature of the eardrum with an infrared sensor. The tip of the thermometer is simply positioned in the ear channel and results are obtained in one second! Next to its convenience this method is very reliable if accuracy can be proven by a clinical validation. Well designed ear thermometers perform very accurately without great scattering in results. An optimised tip shape is the basis for reliable data obtained with infants and babies.

Oral - The oral measurement can be performed as buccal measurement (in the cheek) or as a sublingual measurement (under the tongue). Both measurements underestimate the rectal temperature by approximately 0.3°C - 0.8° C, with the sublingual measurement being preferable to the buccal.

Temple - Temple thermometers offer the least intrusive and therefore most comfortable way to measure body temperature. Simply place the thermometer onto the patient's temple and an infrared sensor detects the peak reading, while a second sensor measures the ambient temperature. The difference in these readings is analysed, and according to clinically established offsets, a body temperature reading is determined and displayed on the LCD.

Armpit - Body surface temperature measurements used clinically in practice are in the arm pit (axillary measurement) and in the groin. In both cases the respective limb is pressed against the body in order to reduce any ambient temperature influence. However, this is successful only to a limited extent with the disadvantage that the measurement time is long. In adults, the axillary measurement is lower than the rectal by approximately 0.5°C to 1.5°C! In infants, these underestimates in comparison with the rectal temperature are much smaller.

Essentially, it is true that the measured body temperature always depends on where it is measured. Therefore, contrary to popular consensus, there is no simple "normal" temperature. Furthermore, a healthy person's body temperature will vary with activity and time during the day. In a rectal temperature measurement, a typical temperature difference of 0.5°C between the higher evening temperatures is physiological. Body temperature is typically elevated after physical activity. Roughly speaking, a distinction is made between a core temperature and a surface, where the surface temperature is measured at the skin surface and is a mixed temperature between the body's core temperature and the ambient temperature. The core temperature is measured by inserting a thermometer into a body cavity, which yields the temperature of the mucous tissue.

Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high. Blood glucose is your main source of energy and comes from the food you eat. Insulin, a hormone made by the pancreas, helps glucose from food get into your cells to be used for energy. Sometimes your body doesn’t make enough - or any - insulin or doesn’t use insulin well. Glucose then stays in your blood and doesn’t reach your cells.

Over time, having too much glucose in your blood can cause health problems. Although diabetes has no cure, you can take steps to manage your diabetes and stay healthy. Sometimes people call diabetes a touch of sugar or borderline diabetes. These terms suggest that someone doesn’t really have diabetes or has a less serious case, but every case of diabetes is serious.

Symptoms of diabetes include:

• increased thirst and urination
• increased hunger
• fatigue
• blurred vision
• numbness or tingling in the feet or hands
• sores that do not heal
• unexplained weight loss

Symptoms of type 1 diabetes can start quickly, in a matter of weeks. Symptoms of type 2 diabetes often develop slowly - over the course of several years - and can be so mild that you might not even notice them. Many people with type 2 diabetes have no symptoms. Some people do not find out they have the disease until they have diabetes-related health problems, such as blurred vision or heart trouble.

The most common types of diabetes are type 1, type 2, and gestational diabetes.

Type 1 diabetes - If you have type 1 diabetes, your body does not make insulin. Your immune system attacks and destroys the cells in your pancreas that make insulin. Type 1 diabetes is usually diagnosed in children and young adults, although it can appear at any age. People with type 1 diabetes need to take insulin every day to stay alive.

Type 2 diabetes - If you have type 2 diabetes, your body does not make or use insulin well. You can develop type 2 diabetes at any age, even during childhood. However, this type of diabetes occurs most often in middle-aged and older people. Type 2 is the most common type of diabetes.

Gestational diabetes - Gestational diabetes develops in some women when they are pregnant. Most of the time, this type of diabetes goes away after the baby is born. However, if you’ve had gestational diabetes, you have a greater chance of developing type 2 diabetes later in life. Sometimes diabetes diagnosed during pregnancy is actually type 2 diabetes.

Other types of diabetes - Less common types include monogenic diabetes, which is an inherited form of diabetes, and cystic fibrosis-related diabetes.

Type 1 diabetes occurs when your immune system, the body’s system for fighting infection, attacks and destroys the insulin-producing beta cells of the pancreas. Scientists think type 1 diabetes is caused by genes and environmental factors, such as viruses, that might trigger the disease. Studies such as TrialNet are working to pinpoint causes of type 1 diabetes and possible ways to prevent or slow the disease.

Type 2 diabetes - the most common form of diabetes - is caused by several factors, including lifestyle factors and genes.

Overweight, obesity, and physical inactivity - You are more likely to develop type 2 diabetes if you are not physically active and are overweight or obese. Extra weight sometimes causes insulin resistance and is common in people with type 2 diabetes. The location of body fat also makes a difference. Extra belly fat is linked to insulin resistance, type 2 diabetes, and heart and blood vessel disease. To see if your weight puts you at risk for type 2 diabetes, check out these Body Mass Index (BMI) charts.

Insulin resistance - Type 2 diabetes usually begins with insulin resistance, a condition in which muscle, liver, and fat cells do not use insulin well. As a result, your body needs more insulin to help glucose enter cells. At first, the pancreas makes more insulin to keep up with the added demand. Over time, the pancreas can’t make enough insulin, and blood glucose levels rise.

You are more likely to develop type 2 diabetes if you are age 45 or older, have a family history of diabetes, or are overweight. Physical inactivity, race, and certain health problems such as high blood pressure also affect your chance of developing type 2 diabetes. You are also more likely to develop type 2 diabetes if you have prediabetes or had gestational diabetes when you were pregnant. Learn more about risk factors for type 2 diabetes.