📘 Insulin Pumps

An insulin pump is an electronic device the size of a small phone that delivers insulin continuously through a thin catheter and cannula placed subcutaneously [1]. It works on the principle of completely replacing the pancreas by delivering a programmable basal rate (basal insulin) at rates of 0.025-2 units/hour (for metabolic needs between meals), plus occasional boluses for meal coverage and hyperglycemia correction. The pump's motor pushes a piston, which in turn pushes insulin from the reservoir through the infusion tube.

Unlike multiple injections, where you use two types of insulin (rapid and long-acting), the pump uses only rapid-acting analog insulin, which through continuous delivery also replaces basal insulin [1]. The pump's software can automatically calculate doses based on previously programmed parameters (insulin-to-carbohydrate ratios, sensitivity factors, active insulin). The system records all deliveries and allows data download for detailed analysis of glycemic patterns.

The main advantage is flexibility [2]. You can have different basal rates for each hour of the day (useful for dawn phenomenon or night shifts), you can temporarily stop insulin for sports or increase basal for illness. Dosing precision is superior, with increments of 0.025-0.1 units compared to 0.5-1 unit with pens. This is essential for young children or people very sensitive to insulin. The integrated bolus calculator automatically accounts for active insulin, preventing dose stacking.

Quality of life improves significantly by eliminating 4-8 daily injections (only one insertion every 3 days), freedom to eat spontaneously without preparation, and discretion in administering a bolus. Studies conducted with modern pumps show HbA1c reduction, decreased severe hypoglycemia, and reduced glycemic variability [2]. Disadvantages include higher cost, technology dependence, constant device visibility, and the need for specific technical education.

Absolutely yes. The pump offers major advantages for sports through the ability to reduce basal rate by 20-80% starting 40-90 minutes before exercise, effectively preventing hypoglycemia without consuming extra carbohydrates [3]. For contact sports (soccer, martial arts) or water sports, you can temporarily disconnect the pump for an hour [4]. You can, for example, first give a compensation bolus of 50% of the missing basal and monitor the effect. Many pumps have specific exercise modes that automatically adjust glycemic targets and insulin sensitivity.

For physical protection, there are special elastic belts, neoprene pockets, or waterproof cases that securely fix the pump on the arm, thigh, or waist. Endurance athletes prefer patch-type pumps without external tubing for maximum freedom of movement. It's important to check glucose before, have fast-acting carbohydrates available, and monitor carefully for at least 12-24 hours post-exercise when insulin sensitivity is higher [5].

Most users place the pump freely in bed next to them, under the pillow, or in the pajama pocket. The 30-110 cm tube provides enough freedom of movement for normal nocturnal turning [1]. You can use a soft waist or arm fixation belt, a special pocket sewn into the pajamas, or even fix it with a sheet clip to prevent tube tangling. Modern pumps have a keypad lock function to avoid accidental presses during sleep.

For couples, the partner quickly gets used to the pump's presence, and temporary disconnection for intimacy is simple and quick. Young children can wear the pump in a special vest or small backpack to prevent playing with the buttons. It's important to check in the morning that the tube hasn't twisted or bent, which could lead to catheter occlusion.

All companies offer replacement within 24-48 hours for warranty malfunctions, and in the meantime, you must immediately return to the multiple injection regimen using backup pens, which you must always have available. Calculate the long-acting insulin dose as the sum of basal rates over 24 hours, and make boluses with rapid insulin using the same ratios and factors. Without insulin in the form of basal rates released by the pump, the risk of ketoacidosis increases rapidly, sometimes in just 2-4 hours [6].

Most malfunctions are actually simple, solvable problems. Check for a dead battery, air bubbles in the reservoir, bent cannula, or occluded infusion set [7]. These are not real pump defects. Always keep an emergency kit with rapid and long-acting insulin pens, urine test strips for ketone bodies, and 24/7 technical support contact numbers. Learn to recognize pump alarms and solve them quickly. Most "malfunctions" reported are resolved by changing the infusion set or restarting the pump.

The infusion set (reservoir, tube, and cannula) is changed every three days, following manufacturer recommendations and individual tolerance [7]. Changing more frequently than three days prevents local infections, lipodystrophy, and decreased insulin absorption due to local tissue inflammation, but adds significant additional costs [8]. The main signs that the infusion set needs to be changed already include unexplained high blood glucose, redness or pain at the insertion site, or insulin leakage.

The optimal time for change is in the morning, to have time to monitor that the new set is working properly. Changing the set before bedtime or before a large meal is not recommended. Systematic site rotation (minimum 2.5 cm distance from previous site) is essential [9]. Use a mental or even drawn diagram to track used areas. Monthly cost for sets represents a significant percentage of total pump therapy cost, being partially or fully reimbursed for certain patient categories.

Standard pumps only deliver doses that you program or confirm. The preset basal rate and calculated boluses that you manually approve before administration cannot be decided by a standard pump [1]. Hybrid closed-loop systems can automatically adjust basal rate every five minutes based on data from the glucose sensor, but still require manual input for meal boluses [10]. The predictive algorithm anticipates glucose evolution 30 minutes ahead and increases, decreases, or stops basal rate preventively. Sometimes it also gives automatic correction boluses.

Even the most advanced current systems are not completely autonomous. They still require manual setting of meal boluses (hybrid system) [10]. Safety limitations prevent delivery of dangerous doses. There are maximum limits for basal rate and bolus that you set. The near future promises fully automated systems (full closed loop), which will no longer require manual meal bolus entry. For now, the pump remains an instrument that requires active and informed use.

You can temporarily disconnect the pump for various daily activities, such as showering, swimming (one hour), intimacy, or other medical investigations incompatible with wearing it [4]. For disconnections under one hour, no compensation insulin is needed. If you want to stay longer without the pump, you can try a bolus before disconnection equivalent to half of the basal that will be missing later. Pump disconnections longer than two hours are not recommended due to the risk of significant hyperglycemia [6].

For longer "pump vacations" (days-weeks), you can temporarily return to pens, with careful dose recalculation and readaptation [2]. Many do this in summer at the beach or on adventurous vacations, where technology is sometimes (rarely) an impediment. Returning to the pump requires fine readjustment of initial settings, as insulin sensitivity may change in the meantime. It's important to always have a backup plan and prevent forced breaks due to lack of supplies or financial problems.

A closed-loop system (artificial pancreas or closed-loop) combines the insulin pump with the glucose sensor and a control algorithm that automatically adjusts insulin delivery based on current glucose estimation and predictions for the next 30-60 minutes [10]. Current commercial systems are "hybrid," meaning they automatically adjust basal rate and some can give micro-correction boluses, while the user manually announces meals and gives prandial boluses [11]. The algorithm learns from your patterns and becomes more efficient after a few days of continuous use.

Studies show that closed-loop systems increase time in target (70-180 mg/dl) from 60% to 70-76%, reduce time in hypoglycemia by 35-50%, and massively improve glycemic control during the night [11]. Current limitations include insulin effect delay due to subcutaneous administration (cannot perfectly prevent post-prandial peaks), need for technical maintenance, and high cost. The future brings bi-hormonal systems (insulin + glucagon), ultra-rapid insulins, and AI algorithms that will bring performance even closer to the natural pancreas [10].