Editorial

Continuous Insulin Infusion Systems in Type 2 Diabetes

Jothydev Kesavadev

CEO & Director, Jothydev’s Diabetes & Research Centre, Trivandrum 695032, India

Abstract

There are various delivery devices available for insulin like syringes, pens, and insulin pumps. Syringes have drawbacks like dosage errors and pain. Insulin pumps can be useful to mimic the physiological insulin secretion. Though the insulin pumps are launched in India a decade ago, they are not popular due to high price and thus there is limited experience and queries with its use. Use of insulin pumps can improve the quality of life for diabetic patients. Available evidence from recent studies is a compelling indication and not to deny the never before discovered benefits of continuous subcutaneous insulin infusion (CSII) in selective patients with type 2 diabetes mellitus . Pumps with continuous glucose monitoring (CGM) system helps as a therapeutic option enabling diabetic patients to restructure lifestyles based on glycemic patterns.

Introduction

Insulin pumps were first launched in India almost a decade ago.1 Latest insulin pumps like Real-Time Insulin Pump with wireless automatic glucose sensing capability have proven to be beneficial not only in lowering the average sugars but also in normalizing glycemic excursions.2 However, considering the limited experience, there are several queries about insulin pump therapy among treating physicians. Being an expensive modality and not being covered by reimbursement or insurance policies in India, though pump therapy is growing in numbers, it is still confined to relatively small number of subjects mainly with type 1 diabetes (T1DM). The objective of this review was to give an overview of insulin pump therapy and address some of the common queries about insulin pump therapy.

Continuous Glucose Monitoring

Continuous glucose monitoring (CGM) system should be regarded as the next revolution in the day-to-day management of diabetes.2,3 Several continuous glucose monitoring devices are being marketed in India. Real-Time insulin pumps are also now available along with continuous glucose sensing technology. The data that has been gathered from CGM has enabled us to learn more about the phenomenon of glycemic excursions, to redefine the so called normal sugars in entities like gestational diabetes mellitus (GDM) and to decide on the basal profiles in patients on continuous subcutaneous insulin infusion (CSII), etc. The CGM data has also helped the scientific community to establish the intimate link between diabetes and cardiovascular illnesses from a different dimension.4 The glucose trends as studied from CGM data offers an explanation for the higher cardiovascular events in diabetes.5

Continuous glucose monitoring is carried out with the help of a tiny sensor needle that is kept subcutaneously, measuring the voltage from the interstitial fluid.6 The voltage is converted to blood sugar values and at the end of 3 days, the entire data can be downloaded to the computer. All such equipments require calibration with the help of an accurate glucometer. Such calibrations are to be carried out when the blood sugars are steady; the reason being when the blood sugars are fluctuating, calibrations, if attempted, may lead to incorrect CGM interpretations. The precision while performing a CGM increases when the instructions are repeatedly provided to the patient and caregivers and when the investigation is done outside the hospital following a normal daily routine. Although CGM as an investigational tool can be carried out both as an out-patient or in-patient procedure, the recordings while performed as an out-patient procedure will be more helpful in terms of translating it to treatment decisions.6

In a recent publication, we have shown that CGM is an invaluable tool in motivated subjects as a therapeutic option enabling them to restructure lifestyles based on glycemic patterns.7

History of Insulin Pumps

Insulin pumps were first developed during late 1960s and early 1970s. 8 Although insulin pumps have got a history dating back to more than 35 years, the modern day insulin pump therapy utilizing sophisticated mini computer devices with customized software were made available only during the last 6–10 years.

The first insulin pump was introduced in the early 60s by a Los Angeles doctor by the name of Arnold Kadish. The first model was so big that it had to be worn on the back in a backpack fashion. The model underwent several clinical tests before it was considered to be a viable alternative to syringe injections, and in the early 80s, it finally gained recognition as a potential replacement to regular insulin delivery for type 1 diabetes patients. The first insulin pump to be manufactured was released in the late 70s. It was known as the “big blue brick” because of its size and appearance. During the initial years, insulin pump therapy became obscured by controversy and was used only in a handful of patients. The results were often unsatisfactory and occasionally disastrous, usually the result of unrealistic expectations or improper application of this technology. In the beginning of the 90s we began to see more user friendly models with features like bolus calculators and compatibility with personal computers so that users can have greater control on their insulin intake and monitor their blood sugars more efficiently.

Real-Time insulin pumps were introduced in 2006, where the glucose sensor and the pump got combined—another key milestone in the history of insulin pump. The introduction of Real-Time insulin pumps was a key breakthrough towards closing the loop, very near to the dream of inventing fully automatic devices.8 There are essential differences between other popular insulin delivery devices, insulin pens and insulin pumps9 (see Table 1).

Indian Data on Insulin Pump Usage

In a study conducted at our center, a total of 46 subjects with T2DM and using multiple daily injections (MDI) were switched over to CSII for 6 months.10 HbA1C, body weight, and total daily dose of insulin were measured before the initiation of CSII and compared with the values 6 months later. After 6 months of CSII, study subjects were asked about their satisfaction with the therapy; they were also asked to assess treatment flexibility, frequency of side effects, and interference with regard to side effects. The mean HbA1C value 6 months after initiation of CSII was 7.6 ± 1.2%, compared to 8.1± 1.4% at baseline while using MDI. The difference in the mean between the 2 groups (0.54%) was statistically significant and the subjects also expressed high overall satisfaction level with CSII after 6 months. The subjects were also asked to assess how CSII affected the sexual function and peripheral neuropathic pain. After 6 months of CSII, 83% of subjects noted an improvement in sexual function as opposed to when they were using MDI. With respect to peripheral neuropathic pain, 87% of subjects reported that they had experienced at least a moderate improvement in symptoms after initiation of CSII.11 In another study conducted at our center involving 52 type 2 diabetic subjects, 48 of themreported tremendous improvement in the quality of life after being deployed with the insulin pumps and 42 achieved A1C below 6.5%.12

In another study published by Sudhakaran C et al.,13 insulin pump therapy was found to be effective in lowering HbA1C in recalcitrant diabetes. Apart from significant reduction in A1C, the reduction in the frequency of severe hypoglycemia and absence of diabetic ketoacidosis was noticed in this retrospective study that followed up T1 subjects (n = 17) and T2 subjects (n = 16) for a mean duration of 3.4 years.

Selecting Subjects for Insulin Pump

Therapy

Insulin pump therapy should never be regarded as a new treatment option. It is only an advanced option to deliver insulin so as to mimic the physiological insulin secretion from a normal human pancreas. International Diabetes Federation (IDF) clinical practice recommendations advocate the use of insulin pumps only in the comprehensive care level. In gestational diabetes mellitus, the treatment can be optimized with the use of CSII in selected cases.

Following are the scenarios wherein we consider CSII at our centre:

1. T1DM or T2DM: In highly selective individuals with strong family support
2. Affordability, both for pump and for the monthly consumables
3. Willing to learn new equipments and materials
4. Willing to follow-up with our diabetes team
5. Frequent hypoglycemic episodes
6. Pregnancy

At our center, the follow up of diabetes patients enrolled under a telemedicine facility is carried out through the telephone or through the website or through the email. 13 Patients who are put on insulin pumps are also managed via this telemedicine program (DTMS(™): Diabetes Tele Management System). They are not hospitalized and the pump deployment is carried out as an out-patient procedure, and all the assistance required in terms of using the pump, modifying the dosages, adjusting the programs in the pump, enquiries on the use of glucometer, insulin pens as rescue medication, etc., is carried out through telephone or through email or through the 24-h helpline. Based on our experience, we emphasize the need for strict selection criteria to go for the appropriate patient for the successful continuation with the insulin pump therapy in type 2 diabetes. In our study, weight gain due to over eating and the use of correction boluses were found to be the major concerns that got corrected later with continuing efforts on educating the patient and motivating the family. Common indications and contraindications14 to insulin pump therapy are given in Table 2.

Follow-up

At least for the initial 1–3 months, a close follow up with diabetes-treatment team in the hospital is essential for the success of insulin pump therapy. Programming the pump and changing the basal and bolus are done gradually so as to normalize blood sugar over a period of time rather than rapidly. Diabetestreatment team taking care of the patient should educate the patient and caregivers on the importance of follow up on a regular basis, and it should be customized for each individual patient, failure of which will result in the failure of pump therapy. The institution should have sufficient pump educators so that patients and caregivers are not only comfortable with the diabetes team but also willing to attend more sessions, which are creative and generate more light into the subject.

Why Pumps are Unpopular in India?

Insulin pumps, although a useful treatment option in diabetes, are still unpopular. The major reason could be the high cost of the equipment and the consumables. Unawareness on the new technology and its incredible benefits are major hurdles. Moreover a multidisciplinary team approach is essential for the successful continuation of the program. As health care providers, we should make every effort in understanding and propagating the technology and skills related to insulin pump therapy. Historically, glucometers, as a glucose measuring equipment, took several decades to get accepted by the patients and by the doctors, and the same evolution could follow with newer delivery devices too.

In summary, at present the three popular delivery devices for insulin are the syringes, pens, and insulin pumps. Despite the initial inconvenience of learning a new technology, it is foreseen that pumps will become cheaper and more popular, offer better flexibility, and improve the quality of life for diabetic patients. Available evidence from recent studies is a compelling indication and not to deny the never before discovered benefits of CSII in selective T2 DM subjects.

References

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