Timing of insulin therapy initiation and blood glucose management in patients with type 2 diabetes

When do patients with type 2 diabetes need insulin treatment?

① When the patient has been using oral hypoglycemic agents for a long time, but the effect is getting worse and worse, and blood sugar cannot be effectively controlled.

② When oral hypoglycemic agents are contraindicated, such as allergic reactions.

③ When liver or kidney function is impaired.

④ When under stress, such as during trauma, surgery, pregnancy, or severe infection, insulin is used to effectively control blood sugar and help the body overcome the stress state.

⑤ When serious complications occur, such as severe diabetic retinopathy, diabetic nephropathy, diabetic foot, or tuberculosis.

How is the initial insulin dose determined? Doctors need to start with a small dose of insulin based on blood sugar levels and gradually adjust the dose. A normal adult secretes approximately 30 IU of insulin per day, so the initial insulin dose should not be too high. ① If fasting blood glucose is <11.1 mmol/L and postprandial blood glucose is <13.9 mmol/L, the daily insulin dose can be 20-30 U, divided into 3 subcutaneous injections before meals.

② If fasting blood glucose is 11.1-16.7 mmol/L and postprandial blood glucose is >16.7 mmol/L, the daily insulin dose is 30-40 U, ​​divided into 3 subcutaneous injections before meals.

③ For diabetic patients over 60 years of age and those with significant heart or kidney disease, if there is no ketoacidosis, the initial insulin dose should be lower. Generally, 8 U, 4 U, and 6 U can be injected subcutaneously 15-20 minutes before breakfast, lunch, and dinner, respectively. The dose should then be gradually adjusted according to blood glucose and urine glucose levels to gradually normalize blood glucose and urine glucose. The initial dose for children is generally estimated based on weight. Children under 10 years old may require 0.5–1.0 U per kilogram of body weight per day, while adolescents aged 10–18 years may require 1.0–1.5 U per kilogram of body weight per day. However, the total daily dose should not exceed 40 U.

How to correctly use insulin?

(1) Determining the appropriate time: In addition to selecting different insulin formulations based on the patient's condition, the appropriate injection time should also be determined based on the formulation and the patient's condition.

① Short-acting insulin should be injected 30 minutes before each meal. The injection dose varies before each meal. The dose before breakfast is the largest, followed by the dose before dinner, and the dose before lunch is the smallest. If an additional injection is needed before bedtime, the dose should be even smaller than the lunch dose. For example, if the daily insulin dose is 30 U, the distribution before each meal is 12 U for breakfast, 8 U for lunch, and 10 U for dinner. For example, if the daily dose is 24U, the distribution before meals is 10U for breakfast, 6U for lunch, and 8U for dinner.

② When using intermediate-acting insulin alone, it should be injected 30-60 minutes before breakfast, or it can be taken before bedtime for better control of fasting blood glucose.

③ Using short-acting plus intermediate-acting or long-acting insulin can reduce the number of injections. If short-acting and intermediate-acting insulin are mixed, the ratio can be (1:1) to (2:1); if short-acting and long-acting insulin are mixed, the ratio can be (2:1) to (4:1). Injection should be done before breakfast and before bedtime.

④ For patients with high fasting blood glucose, to avoid high fasting blood glucose due to late insulin injection, insulin should be injected early before breakfast, preferably no later than 7:00 AM.

(2) Choosing the best injection site: Different injection sites result in different effects.

① Subcutaneous injection is generally used, and suitable injection sites include the outer sides of both upper arms (deltoid muscle), both sides of the abdomen, the buttocks, and the outer thighs. ② Insulin absorption varies across different parts of the body. The forearm and abdominal wall absorb insulin faster than the buttocks and thighs. Areas with hardening or fat atrophy are less likely to absorb insulin and should be avoided.

③ Subcutaneous injection sites should be changed frequently. After two weeks of continuous injections at one site, the site should be changed.

④ Only 75% alcohol should be used for disinfection before injection.

What precautions should be taken when injecting insulin?

① A dedicated syringe must be used. There are three main methods of insulin injection: using an insulin syringe or insulin pen, and continuous subcutaneous insulin injection (insulin pump). It is important to emphasize that ordinary syringes cannot be used because the graduations on dedicated syringes are in insulin units, while ordinary syringes are in milliliters, with the smallest unit being 0.1 ml. This is equivalent to 4 units of insulin, while most patients do not require doses that are multiples of 4.

② When using an insulin syringe to draw insulin solution, different types of insulin require different syringes. For example, a 400U vial of insulin should be drawn using a 40U (1ml) syringe, while a 300U insulin cartridge should be drawn using a 100U (1ml) syringe. Otherwise, dosage errors may occur.

③ Patients using insulin pens should store them at room temperature in a cool, dark place. Generally, insulin pens do not need to be refrigerated. Even in hot summers, most insulin pens come with insulated bags, which are sufficient. Refrigerating the pen can cause inaccurate insulin dosage due to thermal expansion and contraction.

④ If the room temperature is too high (above 25℃) and the patient does not have an insulated bag for storing the insulin pen, and it is necessary to refrigerate the pen, the part containing the insulin cartridge should be unscrewed and stored at 2-8℃. The pen holder with the dose adjustment knob at the back of the insulin pen should not be stored in the refrigerator, as moisture on the knob can affect dosage accuracy.

⑤ Bottled insulin should be removed from the refrigerator 30 minutes before injection and allowed to warm to room temperature.

⑥ Once opened, bottled insulin can be used for up to 3 months at 2-8°C. Once opened, insulin cartridges can be used for up to 1 month at room temperature.

⑦ Insulin syringes and insulin pen needles should be replaced only once. Repeated use can cause significant harm to patients, such as infection, pain, subcutaneous induration, muscle atrophy, and even breakage, ultimately affecting blood sugar control.

⑧ To understand the effects of insulin, its function is indicated in large font: rapid-acting insulin is marked with "R" or "S", intermediate-acting insulin with "L" or "N", and long-acting insulin with "U". 9. When blood sugar is high, injection can be done in the abdomen, injecting slightly deeper, and the interval between meals should be appropriately extended. Eat immediately after injection; if you should not eat immediately after injection, choose the upper arm or buttock, injecting shallower. If blood sugar is normal at the time of injection, any injection site can be chosen, and you can eat normally. If blood sugar is low at the time of injection, choose the upper arm or buttock, injecting shallower, and eat as soon as possible after injection.

How should insulin dosage be adjusted when blood sugar fluctuates in diabetic patients? During insulin use, it is important to monitor blood sugar levels and keep detailed records of daily blood sugar values ​​and insulin dosages. This is crucial and a prerequisite for routine dosage adjustments. In addition, it is necessary to maintain a regular, quantitative daily diet and normal activity patterns. Dosage adjustments should be made under the guidance of a doctor. However, no matter how careful you are, blood sugar levels in diabetic patients will always fluctuate, and sometimes the cause of these fluctuations is difficult to pinpoint. This is not surprising; the key is knowing how to manage and adjust insulin to normalize blood sugar as quickly as possible.

① When pre-meal blood sugar is <3 mmol/L, immediately consume about 10g of glucose or fructose, or drink a sugary beverage. If a routine insulin injection is scheduled for 10-15 minutes later, the insulin dose can be reduced by 2 units compared to usual. Eat immediately after insulin injection, without waiting 30 minutes as usual.

② When pre-meal blood sugar is 3-8 mmol/L, inject the usual insulin dose; no dose adjustment is necessary. Eat 20-30 minutes after insulin injection.

③ When pre-meal blood sugar is 8-11 mmol/L, increase insulin by 2 units, or appropriately reduce the amount of food consumed at that meal, such as reducing a glass of milk or an egg. Eat 30-40 minutes after insulin injection. ④ When pre-meal blood glucose is 11–14 mmol/L, increase insulin by 2 U or appropriately reduce the amount of food consumed at the meal. Wait 40–50 minutes after insulin injection before eating.

⑤ When pre-meal blood glucose is 14–20 mmol/L, increase insulin by 2–4 U or appropriately reduce the amount of food consumed at the meal. Wait 1 hour after insulin injection before eating.

⑥ When pre-meal blood glucose is >20 mmol/L, increase insulin by 4–6 U or appropriately reduce the amount of food consumed at the meal. Wait 1 hour after insulin injection before eating.

⑦ If elevated blood glucose is detected outside of mealtimes, and there are no symptoms, there is no need to immediately increase insulin. Wait until before the meal to measure blood glucose again. If it is still high, then increase the pre-meal insulin dose or reduce the amount of food consumed, depending on the situation. If bedtime blood glucose is not higher than 11 mmol/L, there is no need to increase the insulin dose. This is because, in addition to controlling high blood glucose at night, it is more important to prevent hypoglycemia. If bedtime blood glucose is lower than 6 mmol/L, a small snack should be eaten before bed.