Building Competency in Diabetes Education THE ESSENTIALS

BASAL-BOLUS INSULIN THERAPY | 12-16

BASIS OF INSULIN THERAPY: PHYSIOLOGICAL REPLACEMENT OF INSULIN

Why is “acting like a pancreas” so much easier said than done? Fuel metabolism is regulated by several hormones: insulin, glucagon, amylin, GLP-1, catecholamines, cortisol and growth hormone. The central nervous system (CNS) also plays an important, yet not clearly understood, role in meeting energy needs and maintaining BG levels within a very tight range. The normal BG curve following the ingestion of carbohydrate demonstrates this narrow range that is so difficult to mimic (38,39). Endogenous insulin is produced in two patterns: basal and bolus rates. Secretion of basal insulin is both relatively constant and relatively low; basal insulin is present in sufficient amounts to restrain lipolysis and glucose production. During periods of fasting or exercise, basal insulin levels fall, allowing stored fuel to be released as glucose. Insulin levels are closely linked to glucose levels and rise or fall with glucose levels. After a meal or ingestion of a carbohydrate snack, the postprandial insulin level rises sharply and quickly to a level many times greater than the basal rate (38) (Figure 2). See Chapter 3: Pathophysiology, for more detailed information.

Figure 1. Glucose homeostasis: Daytime profile (40)

CI = confidence interval