High HbA1c despite MDI
Although MDI in a basal-bolus regimen is currently the most popular regimen used in the treatment of insulin-requiring T2DM, many patients fail to attain target levels of HbA1c even when prescribed this regimen. Possible causes could be failure to match insulin doses to the patient's needs, unsuspected hypoglycemic episodes leading to rebound hyperglycemia, and lack of adherence to the regimen leading to missed doses. In such patients, insulin pump therapy will help to deliver the prescribed dose in a more physiological manner, minimizing hypoglycemic episodes and ensuring patient compliance. The total daily dose of insulin can also be brought down when switched over to insulin pump.
Studies have shown improvement in QOL with use of insulin pumps in such individuals probably because of multiple factors like reduction in HbA1c, maintenance of ideal body weight, minimizing glycemic excursions and hypoglycemic episodes, and significant improvement in neuropathic pain.15
CSII may be an effective therapy to reduce insulin resistance in obese T2DM patients without the deleterious side effects associated with increasing insulin dosage.
Insulin resistance remains the predominant factor that may lead to higher HbA1c despite the MDI regimen. Obese T2DM patients with severe insulin resistance tend to develop chronic hyperglycemia, despite maximal intervention with diet, physical exercise, and oral hypoglycemic agents. Insulin therapy in these patients usually does not lead to satisfactory glucose control, even when the insulin dosage is very high. High doses of insulin also cause weight gain, which aggravates insulin resistance and exacerbates other cardiovascular risk factors.
In a study conducted among obese T2DM subjects, CSII was found to reduce total dose of insulin, HbA1c, body weight and the incidence of both postprandial hyperglycemia and severe hypoglycemia.16
A total of 10 severely obese (body mass index, >30
) T2DM patients with severe insulin resistance (insulin dose of >1
U/kg/day) were recruited from a hospital-based practice. Subjects who qualified for the study had an HbA1c >8.5%, despite strict diet and compliance with the insulin regimen. All subjects in the study had a reduction in insulin requirements, from 1.46
SD) at week 0 to 1.19
units/kg/day at week 40. Concomitantly, there was a slight decrease in weight, from 95.9
kg at week 0 to 93.4
kg at week 40. Most significantly, glycemic control improved, with a decrease in the HbA1c levels from 12.34
1.74% at week 0 to 9.56
0.76% at week 40.
In the presence of insulin resistance with high doses of insulin requirements, insulin pump therapy will not only help in normalizing the glycemia but will also help reduce the total daily dose of insulin.
Brittle diabetes is characterized by constant, unpredictable fluctuations in blood sugar levels in spite of consistent diet, exercise patterns, and medication use. It is a challenge to the physician, patient, treatment team, and caretakers and caregivers at home and in office. Brittle diabetes is often encountered in T2DM subjects with a long history of uncontrolled diabetes and advancing age.17
The insulin pump, because of its unique mechanism of preprogramming different basal profiles, enables use of up to 48 profiles per day (for example, with the Medtronic MiniMed Paradigm 715 or 722 pump), which is impossible with any other existing insulin regimen. Moreover, the patient can measure his or her blood glucose values before each meal and can decide on the exact dose of insulin to be administered using the Bolus Wizard (Medtronic MiniMed) function of the pump. This will avoid insulin stacking (active insulin that is left from a previously administered bolus) and the consequent hypoglycemia. Over time the subject can maintain near normal glycemia with lower insulin doses and fewer insulin injections.
Patients with frequent, serious symptomatic hypoglycemic episodes
The insulin pump delivers its basal infusion at miniscule rates, typically ranging from 0.1 to 2
U/h. Such small amounts of insulin are very unlikely to produce hypoglycemia. Moreover, the insulin used in the pump is regular insulin or rapid-acting insulin analogs, both of which have a short half-life and are rapidly degraded, thereby minimizing the risk of accumulation of insulin and subsequent hypoglycemia.
As far as the bolus administration is concerned, new “smart” insulin pumps come with varied features where patients or caregivers can program the functions like the insulin sensitivity factor during different times of the day and also make use of the Bolus Wizard function to calculate and administer insulin according to the varying carbohydrate content of the diet and blood glucose values. Such advanced functions when judiciously used result in physiological insulin secretion mimicking a normal human pancreas. So when insulin is administered properly using an insulin pump, there is no reason for which extra insulin is delivered. When insulin is administered with the help of the Bolus Wizard function, it will also take into consideration the phenomenon of bolus on board or insulin stacking, which is the bolus available in the blood stream from a previously administered bolus. This will also prevent further episodes of low sugars. All the studies have shown either minimal or absolutely no episodes of hypoglycemia occurring when patients are switched over to CSII.16
Patients seeking improved QOL while on insulin shots
Studies comparing those on insulin pumps to those on injections taken with a syringe or pen have shown a remarkable improvement in physical QOL when they were switched over to insulin pumps. Studies have also shown improvement in the pain of neuropathy or disappearance of symptoms of neuropathy in patients when using insulin pumps in T2DM. This disappearance of neuropathic pain has shown to occur within a period of 10–20 days of initiating insulin pump therapy.7,15,18
A patient who is on injections with a syringe or insulin pen needs to take injections on a scheduled basis. The insulin pump offers patients more flexibility with respect to meal timings and meal contents. An insulin pump also allows the patient switch over to a temporary basal at times of exercise or delayed food, thus reducing the dose of insulin that is delivered, thereby preventing hypoglycemic episodes and simultaneously retaining the advantages of continuous insulin infusion. On the other hand, when the patient consumes a meal rich in protein or fat, functions like square wave bolus or dual wave bolus that are available in modern insulin pumps offer better flexibility in lifestyle that can never be replicated with use of other injection devices or insulin regimens. Whether it is an unexpectedly delayed meal, unexpected exercise, or the presence of illnesses that require higher doses of insulin with higher frequency of shots, in all circumstances use of an insulin pump scores over conventional shots. Considering all these factors, it is not surprising that patients who switch over from MDI to CSII invariably report significant improvement in QOL.
Chronic kidney disease on dialysis or post-renal transplant patients
Chronic kidney disease is a condition where there is change in physiology of insulin metabolism and action. In such a situation even small doses of insulin can produce severe hypoglycemia. After renal replacement therapy, when the patient is usually put on steroids and immunosuppressants, there is often a profound rise in blood sugar values requiring high doses of insulin. In those patients who are on dialysis, insulin requirement changes day by day, typically being high immediately after dialysis and low on other days. With the help of “smart” insulin pumps, chronic kidney disease patients can manage blood glucose day to day and day after day with different basal profiles, use the functions like extended bolus, tiny doses of rapid-acting insulin to control high blood sugars without the risk of hypoglycemia.
Frequent travelers and those with untimely food habits
In those who are frequently traveling, especially businessmen, who may be actively involved in job discussions and meetings with untimely food habits, insulin pump therapy offers complete flexibility in their lifestyles. In those who are traveling within the country or from one country to another, where time zones change, smart pump offers the advantage of switching from one profile to another with the hit of a button. Depending on the type and timing of food and change in timing of exercise, travelers with diabetes will find it quite easy to manage their sugars intelligently with the help of a pump.
Micro- or macrovascular complications where intensive glycemic control may be beneficial in the long term
The Diabetes Control and Complications Trial (DCCT),8
the United Kingdom Prospective Diabetes Study (UKPDS),9
Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE),19
and similar international trials have proved the benefits of intensive glycemic control in preventing complications of diabetes. The only demerit of an intensive management regimen is the occurrence of hypoglycemia, which can be minimized or totally avoided when proper use is made of insulin pumps. Whenever management of T2DM is attempted with a goal of preventing micro- and macrovascular complications in the long term with intensive control of glycemia, insulin pumps can be used. Patients with early diabetes complications (microalbuminuria, early retinopathy, etc.) stand to gain particularly from tight control as it will help in preventing the progression of these complications.
Continuous glucose monitoring patterns strongly suggesting the need for a variable basal insulin infusion rate
Continuous glucose monitoring (CGM) is advocated for monitoring blood glucose continuously over a period of 3–6 days or more. CGM presents data on blood sugar pattern that can never be obtained with the help of blood sugar meters. CGM is similar to a video, providing blood glucose pattern over several days, whereas self-monitoring of blood glucose can only provide values similar to that of a picture that is less descriptive. Whenever a CGM pattern strongly indicates utilization of insulin pump therapy, patients can be advised to go in for the same. The Somogyi or dawn phenomenon, clearly interpreted by CGM, can be easily resolved with changes in the basal infusion profiles of the pump. However, with the use of currently available insulins and insulin regimens, such programming of basal profiles is next to impossible.
Modern insulin pumps give us the opportunity to go for up to 48 different basal profiles; however, an average T2DM patient will usually require only three or four basal profiles for minimizing or normalizing glycemic excursions and combating the dawn or Somogyi phenomenon.
Women with poor diabetes control in the childbearing age group contemplating starting a family or who are currently pregnant
With T2DM increasingly affecting younger individuals, there has been an increase in the number of women in the childbearing age with T2DM. Tight control of blood sugars is essential for a successful pregnancy outcome in these women, and the tight control should begin before conception. The need for good control is even greater if the woman has a bad obstetric history or is undergoing assisted reproductive procedures like in vitro fertilization. Often, control of blood sugars during pregnancy is difficult because the wide fluctuations in insulin requirement due to hormonal changes. Also, both hyper- and hypoglycemia episodes are deleterious to the fetus and must be avoided. Use of an insulin pump during pregnancy can help in maintaining near-normoglycemia throughout the pregnancy.20