insulin is given as one or two shots each day, and it activates slowly after injection. This means that some amount of insulin will always be present in the blood. The blood can then bring insulin to the cells throughout the body, and glucose can then enter the cells, where it is converted into energy. In the liver, insulin helps regulate the slow release of stored glucose to meet the energy needs of the body’s cells between meals and during the night.
Bolus insulin is given as rapid-acting insulin. It is activated much faster after injection and brings the large amount of glucose from your meals into your body’s cells. There, glucose can be used right away for energy or stored for later use. Boluses with rapid-acting insulin can also be used to decrease a high blood glucose level. These doses are called correction boluses.
The difference between an insulin pump and MDI is that an insulin pump just uses rapid-acting insulin to do both jobs. The basal rates on the pump replace the basal insulin injection in MDI, and boluses given at meals and for correction replace the mealtime and correction shots.
KNOW YOUR GLUCOSE AND A1C TARGETS
What is the ultimate goal of diabetes treatment? To effectively manage diabetes day to day, so that glucose levels are in the right range—known as the target range—as much as possible to avoid highs and lows. Keeping glucose levels in the target range minimizes your risk of the short- and long-term complications. The target range for glucose is different at different times of the day. For example, in the morning when you haven’t eaten for several hours (fasting), your target will be lower than it is after meals, when blood glucose is highest. Overnight, when you are sleeping, your target may be higher than the fasting range to protect you from hypoglycemia.
The American Diabetes Association (ADA) has established general target ranges for glucose levels throughout the day for different age groups. Generally speaking, younger children have higher targets for their glucose levels. In addition, there are a number of conditions that might lead the diabetes team to suggest higher targets, such as having repeated low blood glucose (hypoglycemia), being unaware of the symptoms of hypoglycemia (referred to as hypoglycemia unawareness), or having diabetes complications. You should discuss this with your diabetes team and find out what your target range glucose levels should be throughout the day and night.
Similarly, you should be aware of the target range for your A1C test. A1C measures the percentage (%) of your hemoglobin (a protein in red blood cells) molecules that have glucose attached to them. The higher your average glucose levels day after day, the higher your A1C. It gives you a good picture of what your blood glucose levels have been in general over a longer amount of time. A1C should be measured every three to four months, and you should know what your level is each time it is taken. A1C is often referred to as the diabetes report card. By seeing if your A1C is in the target range set by your diabetes team, you can know if your diabetes control is optimal.
RESEARCH SUPPORTS MDI AND INSULIN PUMP THERAPY
There have been a lot of research studies in the fields of MDI and insulin pump therapy, and many of them have shown that there are potential benefits in diabetes care. Here are some studies that have helped us better understand how to manage diabetes and how MDI and particularly insulin pump therapy can be a useful tool.
The Diabetes Control and Complications Trial (DCCT)
Before the mid-1990s, someone with type 1 diabetes would take one (maybe two or, rarely, three) insulin injections per day. Back then, regular, NPH, lente, and ultralente insulins were in use. Except for NPH and regular, these other insulin preparations are not available today. Insulin doses weren’t adjusted from one day to the next, which meant that people had to follow a strict eating plan and physical activity regimen. That meant you couldn’t skip breakfast, you couldn’t delay having lunch, and if you routinely had a snack in the afternoon, you had to eat one even if you weren’t hungry! Although you might have taken fewer shots, the trade-off in having a fixed diet and activity pattern wasn’t worth it—and more importantly, this regimen led to inadequate diabetes control.
The Diabetes Control and Complications Trial (known as the DCCT) was a nine-year study. When the results were reported in 1993, the concept of how diabetes should be managed was changed forever. The investigators proved that tighter glucose control using MDI (three or more shots per day) or insulin pump therapy was better than conventional therapy at lowering A1C and reducing the risks of developing diabetes complications.
The DCCT conclusively showed that blood glucose control matters. Although the youngest participants in the DCCT were 13 years old when they entered the study, the overall results of the DCCT have been generalized to all of type 1 diabetes: effective blood glucose control is the most effective way to reduce the long-term complications of diabetes.
Over 1,400 people with type 1 diabetes took part in the study. They were divided among two groups: one for intensive management and the other for conventional therapy (the way diabetes used to be managed). The intensive group used MDI (three or more shots per day) or an insulin pump. This group also received a great deal of support from the study teams. At the end of the DCCT, the people who used MDI had an average A1C level of 7.4%. Those receiving conventional therapy took one or two shots a day, and did not have blood glucose targets or a lot of support from the study teams. Their average A1C levels were 9.1%. Nine years later, those in the intensive group had fewer severe eye, kidney, and nerve problems than those in the conventional group. This was a stunning discovery. However, the other lesson from the DCCT was that lowering A1C levels increases the risk of hypoglycemia.
Epidemiology of Diabetes Interventions and Complications (EDIC)
After the DCCT concluded in 1993, a follow-up study began, and it is still running today. The study is called Epidemiology of Diabetes Interventions and Complications (EDIC), and almost all of the DCCT participants entered into it (but they did return to their previous health care teams, not the study teams). By 2009, those who had been in the intensive group had lower rates of eye disease, kidney disease, and cardiovascular disease when compared with those in the conventional group. Although the people in the intensive group did see an increase in their average A1C levels over this period, there was still convincing evidence that intensive management and improved A1C levels provide noticeable health benefits, even if the therapy was provided years before. That is why considering an insulin pump to manage your diabetes makes sense.
LESSONS FROM DCCT AND EDIC
After 30 years of diabetes, fewer than 1% of participants in the intensive group had become blind, required kidney replacement, or had an amputation because of diabetes.
Other Studies and Guidelines
Many studies have evaluated insulin pump therapy. Although none have had the scientific rigor of the DCCT, overall they show that insulin pump therapy decreases A1C, and now it has also been shown to reduce rates of hypoglycemia. These studies have been done across age groups, for different conditions (such as pregnancy or severe hypoglycemia), and in many places around the globe. There have been 11 studies that compared insulin pumps to MDI, and across all of them, A1C was approximately 0.5% lower in those using insulin pumps. Regardless of who is using the insulin pump, the studies have shown an overwhelmingly positive benefit.
Studies
