01 

Regular Syringes 

Regular syringes were the first tools to be used for injecting insulin.Regular syringes are graduated in milliliters (ml), with the smallest unit being 0.1 ml.Regular syringes can be used for drawing insulin from bottles, and cannot be used for drawing insulin from refills. Typically 0.1 ml of regular insulin is drawn, representing 4 units of insulin.

Since the dose of insulin a patient needs to inject is usually not a multiple of 4, there are some problems with injecting insulin with a regular syringe: 

Cumbersome conversions are needed to determine how much liquid needs to be withdrawn; 
It is difficult to accurately control the actual dose of insulin to be injected.

02 

Insulin-specific syringes 

Insulin-specific syringes are designed to meet the special needs of insulin injection. The insulin dosage is taken as a unit, and the unit is drawn according to the actual dosage when used. There are 2 different sizes of insulin special syringes: U-40 and U-100. 

U-40 is suitable for insulin injections of 40 units per milliliter; U-100 is suitable for insulin injections of 100 units per milliliter, and you need to choose according to the concentration of insulin injections when you use it.

Insulin-specific syringes are more precise than ordinary syringes, but there are still some drawbacks: the need to draw insulin before each injection, inconvenience in carrying and injecting, and obvious pain in injecting with longer needles.

03 

Insulin Injection Pen 

Insulin Injection Pen is a convenient and precise insulin injection device, specialized in insulin injection. The shape of insulin injection pen is similar to that of fountain pen, and it can be divided into insulin pre-filled injection pen and refillable injection pen.

Insulin prefilled injection pens are disposable injection devices, and the pens are discarded directly after the refills are used up.
The refillable injection pen consists of an injection pen and an insulin refill, and the injection pen can be reused, and the refill can be replaced with a new refill for continued use after the refill is used up.
The insulin injection pen is easy to operate, the patient does not need to draw insulin, according to the required dose rotate the dose scale of the injection pen can be used.

Usually the minimum scale for each adjustment of insulin injection pen is 1 unit, some manufacturers of insulin pens can accurately adjust the scale to 0.5 units, this half-scale insulin pen is suitable for insulin-sensitive or infant type 1 diabetes patients.

04 

Electronic Insulin Injector Pen 

The electronic insulin injector pen has a more precise graduated scale that allows for tiny dose adjustments as compared to a regular insulin injector pen. Electronic insulin injection pens have a starting insulin injection dose of 0.5 units, which can then be increased in 0.1 unit adjustments.

Most electronic pens have a Bluetooth transmission feature that connects to the patient's mobile device and transmits in real time the data generated by the patient during the use of the injection pen, which allows the patient to view, record, share, and track information about each insulin infusion. The electronic insulin injection pen can help patients control their insulin dose more accurately and is suitable for insulin-sensitive diabetic patients.

05 

Insulin Pump 

Insulin pump, also known as Continuous Subcutaneous Insulin Infusion System (CSII), is an insulin infusion device that uses artificial intelligence control to continuously infuse insulin subcutaneously at a programmed rate, mimicking the sustained basal secretion of physiological insulin and pulsatile release at meal times to achieve more precise blood glucose management.

Most insulin pumps set basal and mealtime insulin by manually adjusting the rate.

Basal insulin can be set to different basal rates at different times according to the patients' blood glucose fluctuation pattern to cope with the dawn phenomenon or dusk phenomenon that may occur in the patients, etc.; 
Mealtime insulin can be set to different infusion modes (regular wave, square wave, double wave) according to the patients' food type and meal time to make the patients' postprandial blood glucose control reach the standard.
Some new insulin pumps also incorporate continuous glucose monitoring (CGM) technology, which automatically calculates and adjusts insulin dosage according to real-time glucose information, realizing closed-loop control of blood glucose, and more accurately mimicking the function of the human pancreas, which is also known as the “artificial pancreas”.
Insulin pumps can maximize the simulation of the physiological secretion pattern of human insulin, reduce the risk of hypoglycemia and improve blood glucose fluctuations. Compared with other insulin infusion devices, insulin pumps are easy to operate, effective in lowering glucose and avoid the pain of repeated subcutaneous injections.

06 

Needle-free syringes 

Needle-free syringes, also known as insulin high-pressure syringes, are infusion devices that instantly penetrate the epidermis of the human body to the subcutaneous tissue through high pressure.

Compared with needle syringes, needleless syringes have a faster time to peak after injecting short-acting human insulin or rapid-acting insulin analogs and are less prone to subcutaneous fat hyperplasia with prolonged injections. The starting dose of insulin injected with needleless syringes varies among manufacturers and is usually 4 or 5 units.

Needle-free syringes are a better choice for patients who have a fear of needles and must inject insulin, avoiding the pain and anxiety associated with traditional needle injections. However, this device is expensive and more cumbersome to operate, and some patients may develop skin redness, subcutaneous bleeding or ecchymosis, and it is not yet widely used in clinical practice.

The information is from the Internet and is for reference only.