Hypoglycemia in some special situations

Basal insulin is never stopped, not even on days when you eat nothing at all, because you need it all the time [1]. It is a good idea to have a sick-day plan made in advance with your doctor [2]. The plan says what you can drink, how often you need to test your blood glucose and ketones and when to contact your care team [2]. Fever and infections usually increase the need for insulin, and a lack of enough insulin can lead to ketones [3]. If you use an automated insulin delivery (AID) system, the algorithm may adapt too slowly to the high insulin needs of sick days [2] [3]. That is why the pump sometimes needs to be switched to manual mode [2].

The risk of hypoglycemia rises when you eat less or nothing at all. In this situation, the mealtime insulin dose is reduced or skipped, and the basal insulin dose may be reduced as your plan says [3]. If your blood glucose stays below 250 mg/dL (13.9 mmol/L), you can have drinks that contain carbohydrates [3]. If it is above this value, it is better to have only sugar-free drinks [3]. Go to the emergency department if your blood glucose stays below 70 mg/dL (3.9 mmol/L) even though you have treated the hypoglycemia several times [1] [3]. Also go if you cannot drink fluids or if your blood ketones stay above 1.5 mmol/L [1] [3]. The table below sums up the rules for blood glucose that is too high or too low.

Yes, because the carbohydrates from food are no longer absorbed, while the insulin dose keeps working [3]. The most common cause of hypoglycemia on sick days is an infection of the stomach and intestines (gastroenteritis). Hypoglycemic episodes can continue for a few days after the vomiting stops [3]. Test your blood glucose and ketones every 1–2 hours, because vomiting can also be a sign of a lack of insulin [3]. If ketones appear while your blood glucose is low, they usually show that your body is not getting enough energy from food [3]. That is why you need more carbohydrates, together with the insulin for them [3].

In children who vomit or eat very little, especially after the mealtime insulin dose, a small dose of injectable glucagon can prevent hypoglycemia [4] [5]. The glucagon from the classic kit is used, injected subcutaneously with an insulin syringe, when blood glucose has already reached 80 mg/dL (4.4 mmol/L) or less [5]. The usual dose is two units on the syringe up to the age of two, then one unit for each year of age, at most 15 units [5]. If blood glucose does not rise within half an hour, double the initial glucagon dose is injected [4] [5]. If the vomiting lasts more than two hours or the hypoglycemia does not get better, it is better to go to the emergency department [3]. Do not drive there alone, because hypoglycemia at the wheel is dangerous. Ask someone to take you or call the emergency number.

A safe journey starts with careful preparation [2]. Flights can bring problems at airport security, larger swings in blood glucose and difficulties in carrying insulin correctly [6]. Always take an extra supply of insulin, test strips and sensors and keep all your diabetes supplies in your hand luggage [2]. In the hold of the plane insulin can freeze, which reduces its effect afterwards [3]. Always show your pump and sensor at security and check in advance what the manufacturer recommends for flights [2].

Meals at unusual times, heat and a lot of walking call for closer monitoring of how your blood glucose changes [2]. On the plane, the mealtime insulin dose is taken before the meal, based on what you eat [7]. Insulin should not be left in a vehicle heated by the sun, nor should it freeze in the hold of a plane [8]. An opened insulin cartridge or pen is usually kept at room temperature, below 30 °C, for no more than 28 days [8]. The time limit differs by type of insulin, so check the package leaflet [8]. Carry a medical ID card in the local language that says you have type 1 diabetes and may need help in case of hypoglycemia [2].

Yes, because meals shift, and insulin doses and their times are harder to adapt to the new schedule [7]. Up to one in ten insulin-treated patients who travel abroad have hypoglycemia on the way or on the first day after arrival [7]. If you cross fewer than five time zones or stay for less than three days, basal insulin is still taken at your home time [7]. If you cross five or more time zones, the day gets shorter going east and longer going west, so the basal insulin dose is adjusted only once [7].

When you travel west, only on the day of travel, the basal insulin dose is usually split into two halves [7]. One is taken at your home time, and the other at the same time by the local clock [7]. When you travel east, a single basal insulin dose reduced by 10–20% is taken, then you return to your usual regimen from the next day [7]. If you use a pump, the pump clock is changed on arrival, so the basal rates adapt immediately to the local time [7]. The plan is made with your doctor before you leave, and in the first days it is a good idea to test your blood glucose more often [2] [7].

Yes. Fasting increases the risk of hypoglycemia, dehydration, hyperglycemia and even ketoacidosis [9]. If you have type 1 diabetes, the risk is generally quite high, but it differs from one patient to another, so it is assessed individually before the fast [9] [10]. Most hypoglycemic episodes occur toward the end of the fast, especially in the last hours [9] [10]. That is why, during this period, it is a good idea to test your blood glucose as often as possible and to avoid intense physical exercise [9] [10].

The plan is made together with your doctor 6–8 weeks before the fast [10]. The basal insulin dose is usually reduced by 10–30% [10] [11]. If you take it with the evening meal that ends the fast each day, the reduction can reach 40% [10] [11]. If you use a pump, the basal rates are reduced by 20–40% in the last 3–4 hours of the fast [10] [11]. A sensor is the preferred method for monitoring blood glucose [10] [11]. Testing with a glucometer does not break the Ramadan fast [10] [11]. The fast is broken immediately if blood glucose falls below 70 mg/dL (3.9 mmol/L), even without symptoms, or if it rises above 300 mg/dL (16.7 mmol/L) [10] [11]. The fast is also broken if there are signs of dehydration or acute illness [10] [11]. The evening meal that ends the day's fast often contains somewhat more sugar and fat, so it needs a carefully chosen insulin dose [9].

Tell the staff in advance that you use insulin and try to get an early-morning appointment, so that the fast is as short as possible [12]. Basal insulin is not stopped, because the body needs it even when you have not eaten [12] [13]. Before surgery, in adults, usually 75–80% of the usual basal insulin dose is taken on the evening before [13]. The mealtime insulin dose is not taken if you do not eat.

Preparation for a colonoscopy, with clear liquids from the day before, provides few carbohydrates, and fasting increases the risk of hypoglycemia. Take a fast-acting source of glucose and your glucometer to the hospital, test your blood glucose in the waiting room and tell the staff you have type 1 diabetes. The pump can stay on during the procedure if the hospital rules and the type of procedure allow it [12] [13]. If hypoglycemia occurs, it must be treated immediately with glucose or juice, even if you are fasting, and the test may be rescheduled if needed.

Yes, because a child under six usually cannot recognize, describe or treat hypoglycemia on their own [14]. At this age, the signs of hypoglycemia are often limited to changes in behavior, such as irritability, restlessness, unusual quietness or tantrums [5]. Severe hypoglycemia, ketoacidosis and long-term hyperglycemia can affect brain development in children under six [14].

For treating hypoglycemia, the amount of glucose is calculated by weight, about 0.3 g per kilogram of body weight, for example 9 g for a child weighing 30 kilograms [5] [15]. A sensor is recommended from diagnosis, and AID pumps should be offered to all children who can use them safely, on their own or with their family [14]. In children aged 2–5 years, the AID pump increases time in the target range, without an increase in time spent in hypoglycemia [16]. All adults who care for the child, including at nursery school, must learn to recognize hypoglycemia and to use glucagon [5].

Yes. More and more patients with type 1 diabetes reach old age, because their life expectancy has risen greatly in recent decades [2] [17]. At this age, the risk of hypoglycemia rises because of irregular meals, declining kidney function, memory problems and a large number of medicines [18] [19]. In older adults, the signs of hypoglycemia much more often include confusion, disorientation or dizziness and less often trembling, sweating and a fast heartbeat [19]. In older adults with long-standing type 1 diabetes, severe hypoglycemia is often associated with impaired awareness of hypoglycemia and with large swings in blood glucose [20].

Glycemic targets are chosen according to state of health, not age, and insulin regimens can be simplified if needed [2] [18]. A sensor is also recommended for older patients with type 1 diabetes [18]. In patients aged 60 or over, a sensor almost halves the time spent in hypoglycemia [21]. AID pumps also reduce hypoglycemia, including in older adults who are healthy or have memory problems that are still mild [2] [18]. Family members or caregivers must learn to recognize hypoglycemia and to use glucagon, and the sensor can support them by sending the data automatically, if it has this function [2].

Yes, especially in the first trimester and after childbirth [22]. In pregnancy, the hormonal response to hypoglycemia changes, and hypoglycemic episodes are harder to recognize [22]. Nausea and vomiting in the first half of pregnancy and stricter glycemic targets also increase the risk of hypoglycemia [2] [22]. Right after childbirth, the need for insulin falls sharply and can be about a third lower than even before pregnancy [2] [22]. Breastfeeding also increases the risk of hypoglycemia [2] [22].

A sensor is recommended for all pregnant women with type 1 diabetes [22]. In pregnancy, time spent in hypoglycemia is counted below 63 mg/dL (3.5 mmol/L) [22]. Using a sensor increases time in the target range, without more severe hypoglycemia in the mother, and newborns have fewer complications [23]. AID pumps with pregnancy targets can be very helpful, but most AID pumps do not have pregnancy targets, so the choice is made with the doctor [2] [22]. It is a good idea for the family to learn early how to recognize and treat hypoglycemia, ideally even before pregnancy [22].

Yes, because heat widens the blood vessels in the skin and speeds up the absorption of insulin [24]. After a sauna, rapid-acting insulin is absorbed about twice as fast, so blood glucose can fall more than on a day without a sauna [25]. Any warming of the skin, such as a hot bath or shower, also speeds up insulin absorption, especially in the first hour after the insulin dose [24].

Before a sauna or a hot bath, a snack or a slightly smaller insulin dose can help prevent hypoglycemia [25]. In these situations you can try giving the insulin dose in an area with slower absorption, such as the thigh [24]. On very hot days it is a good idea to test your blood glucose more often, and remember never to leave insulin in a vehicle heated by the sun [2] [8]. If you use a pump or a sensor, it is a good idea to check in the instructions what their temperature limits are.