Exercise insulin absorption

Injection technique has pharmacokinetic consequences according to whether the insulin is delivered into the subcutaneous tissue or (inadvertently) into muscle. The introduction of a range of appropriate length needles and pen-shaped injectors has enabled patients to inject perpendicularly to the skin without risk of intramuscular injection. The absorption of insulin is as much as 50% more rapid from shallow i.m. injection. Clearly factors such as heat or exercise which alter skin or muscle blood flow can markedly alter the rate of insulin absorption. 

Absorption of insulin is mainly dependent on the preparation used (see Section 2). Insulin is fairly rapidly absorbed from subcutaneous tissues and although its half-life in blood is very short (see below), the duration of action of most preparations is considerably longer because of their formulation (see Section 2). The rate of absorption from different anatomical sites may be different and may also be increased by exercise. The absorption of insulin after intramuscular administration is more rapid than that after subcutaneous administration (Martindale, 1989). Apart from the fact that absorption depends on the site of injection, it is most rapid from the subcutaneous fat tissue in the abdominal region rather than from the leg or the arm. It can be modified by massage of the tissue or by heat, both inducing an increase in subcutaneous blood flow (Berger et al., 1982). 

In a study involving 11 insulin-dependent diabetic subjects, leg exercise accelerated insulin absorption from a subcutaneous injection site in the leg, whereas it had no effect on insulin absorption from the arm and reduced it from the abdomen (Koivisto and Felig, 1978). Most exercise involved many muscle groups, and increased absorption was still likely. Patients who developed hypoglycaemia were advised to take extra carbohydrate before exercise rather than decrease the insulin dose (Zinman et al., 1978). Studies in five subjects suggested that absorption was increased by exercise (Koivisto, 1980a). 

FACTORS THAT AFFECT INSULIN ABSORPTION The degree of control of plasma glucose may be modified by changes in insulin absorption, factors that alter insulin action, diet, exercise, and other factors. Factors that determine the rate of absorption of insulin after subcutaneous... 

Dandona, P., Hooke, D., and Bell, J., 1978, Exercise and insulin absorption from subcutaneous tissue, Med J. 1 479-480. 

Femqvist, E., Linde, B., Ostman, J., and Gunnarsson, R., 1986, Effects of physical exercise on insulin absorption in insulin-dependent diabetics A comparison between human and porcine insulin, Clin. Physiol. 6 489-498. 

Susstrunk, H., Morell, B., Ziegler, W. H., and Froesch, E. R., 1982, Insulin absorption from the abdomen and the thigh in healthy subjects during rest and exercise Blood glucose, plasma insulin, growth hormone, adrenaline and noradrenaline levels, Diabetologia 22 171-174. 

The effects of insulin are modified by various factors. The speed and extent of absorption of insulin depends, for example, on the site of injection (1), the depth of the subcutaneous injection, skin temperature (2), the presence of lipodystrophy, and variation in the extent of inactivation of injected insulin. The disposal of insulin depends on many factors. Exercise and hard work lower the blood glucose and thereby increase the effect of insulin. Infections and obesity reduce its effect. The timing of food intake and the composition of meals are also related to the action of insulin. A thin layer of fat, as sometimes occurs in the upper arm or in the thighs of thin men, can result in intramuscular injection, leading to faster absorption of long-acting insulins. This can reduce the absorption time by half (3). The major factors that affect the fate of injected insulin (and thereby also its risks) are listed in Table 1 (4). 

The second example considered the absorption of soluble insulin from subcutus. The problem here was to establish a set of consistent hypotheses that could explain the observed volume and concentration effects. At the time when the model was formulated there was no notion of the possible role of polymerization in the absorption process for insulin. Most experiments were performed at normal pharmacological concentrations (40 IU/ml) and injection volumes (0.3 ml), and the work was oriented towards elucidating the importance of exercise and skin temperature at the absorption site. Such experiments are obviously important, since variations in skin temperature may pose a problem in the control of labile type I diabetes. Analyses of a single set of data, obtained partly at micro-dose levels, allowed us to identify processes in the skin that were not amenable to direct experimentation. 

Peak plasma insulin (s.c.) concentration is attained in 60-90 min. Absorption is slower if there is peripheral vascular disease or smoking, and faster if the patient takes a hot bath or uses an ultraviolet light sunbed (which may induce a hypoglycaemic fit) or exercises. The effects are due to changes in peripheral blood flow. 

The effects of insulin are modified by various factors. The speed and extent of absorption of insulin depends, for example, on the site of injection (1), the depth of the subcutaneous injection, skin temperature (2), the presence of lipodystrophy, and variation in the extent of inactivation of injected insulin. The disposal of insulin depends on many factors. Exercise and hard work lower the blood glucose and thereby increase the effect of... 

Injected region Absorption faster from abdominal region than from femoral and gluteal regions exercising the injected limb speeds up absorption (applies especially to regular Insulin)... 

Metformin hydrochloride is a biguanide that decreases blood glucose by decreasing hepatic glucose production. It may also decrease intestinal absorption of glucose and increase response to insulin. Metformin is indicated as an adjunct to diet and exercise to lower blood glucose in patients with type 2 diabetes mellitus. Metformin IR tablets and oral solution are indicated in patients 10 years of age and older. The ER tablets are indicated in patients 17 years of age and older. In combination with a sulfonylurea or insulin to improve glycemic control, metformin is indicated in patients 17 years of age and older. 

The absorption rate after intramuscular administration differs depending on type of muscle chosen. Studies have shown that intramuscular injections result in different plasma concentrations of narcotics and perceived pain relief depending oti the type of muscle used for administration. This was also found for the response to vaccination and use of antibiotics and insulin [7]. Absorption of active substances from the intramuscular site depends mi the quantity and composition of the connective tissue and the rate of vascular perfusion of the area. Blood flow in the muscles varies (it is increased in deltoid muscle) and is influenced by the exercise of the muscle and morbidity. The muscles are covered with the subcutaneous connective tissue, a hpid layer (adipose layer) and the skin. The thickness and the Upid content of these tissues are different in different body areas. The subcutaneous fat layer at the gluteal intramuscular injection site is thicker in females (mostly > 3 cm) than in males. The medication should be administered with a needle long enough to reach the muscle without penetrating underlying structures. 

Koivisto, V. A., 1993, Insulin therapy in type II diabetes, Diabetes Care 16(Suppl. 3) 29-39. Koivisto, V. A., and Felig, P., 1978, Effect of leg exercise on insuhn absorption in diabetic... 

Normally, a controlled diet and exercise should help maintain normal blood glucose levels. When these are not sufficient, medication may need to be prescribed. Medications available today either increase the insulin supply (such as sulfonylureas, secretagogues), decrease the insulin resistance, or improve its effectiveness (biguanides and thiazolidinediones) [15]. Another group of medications is called alpha-glucosidase inhibitors, which reduce the rate of glucose absorption. 

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