Medical Nutrition Therapy for Diabetes Mellitus
Manual of Clinical Nutrition Management C- 4 Copyright © 2 013 Compass Group, Inc.
individuals with type 2 diabetes mellitus (16,17). Fiber supplements providing doses of 10 to 29 g/day may
also have some benefit in terms of glycemic control (Grade III) (16). There is conclusive evidence that dietary
fiber intake from whole foods or supplements may lower blood pressure, improve serum lipid levels, and
reduce indicators of inflammation (Grade II) (16). Benefits may occur with intake of 12 to 33 g fiber per day from
whole foods or up to 42.5 g fiber day from supplements (Grade II) (16). For patients with diabetes complicated by
disorders of lipid metabolism, particularly hypercholesterolemia, lower cholesterol levels are an important
benefit of consuming a high-fiber diet (16). Potential gastrointestinal side effects of excessive dietary fiber
should be considered when integrating fiber into meal planning. A gradual increase in fiber from whole foods
and supplements is suggested within recommended ranges to prevent negative side effects (16). Fiber is not
digested and absorbed like sugars or starches. For purposes of carbohydrate counting, when there are more
than 5 g of fiber per serving, half the number of grams of fiber should be subtracted from the total grams of
carbohydrate to determine the amount of available carbohydrate (5).
Resistant Starch
Resistant starch (nondigestible oligosaccharides and the starch amylase) is not digested and therefore not
absorbed as glucose in the small intestine. Legumes are the major food source of resistant starch in the diet;
100 g of cooked legumes contain 2 to 3 g of resistant starch, and 100 g (dry weight) of cornstarch contains
about 6 g of resistant starch (18). It has been suggested that resistant starch produces a smaller increase in the
postprandial glucose level than digestible starch and corresponds to lower insulin levels (2). Studies of
persons with diabetes have focused on uncooked cornstarch and its potential to prevent nocturnal
hypoglycemia. Some studies have demonstrated less hypoglycemia when cornstarch snacks are used;
however, the evidence is limited. There is currently no established benefit of resistant starch for people with
diabetes (2).
Timing of Carbohydrate and Food Intake: Type 1 Diabetes
For individuals requiring insulin, the total carbohydrate content of meals and snacks is the first priority and
determines the premeal insulin dosage and postprandial glucose response (1-4,19). Individuals receiving
intensive insulin therapy can adjust the premeal insulin dose based on the amount of carbohydrate at meals
to maintain their blood glucose goals (Grade I) (4). Individual needs should dictate the time when meals and
snacks are eaten, how much time elapses between insulin injection and food intake, and the number of meals
and snacks (1). Self-monitoring of blood glucose levels is necessary to achieve optimal blood glucose control
and to prevent or delay the onset of diabetic complications (4). Checking blood glucose levels three to eight
times per day has been associated with better glycemic control regardless of diabetes type or therapy (Grade I)
(4). The American Diabetes Association recommends that people with type 1 diabetes or pregnant women
who take insulin check their blood glucose levels three or more times daily, so that they can adjust food
intake, physical activity level, and/or insulin dosage to meet blood glucose goals (1). Day-to-day consistency
of food consumption is crucial for individuals who inject a fixed daily dosage of insulin (1,2).
For individuals who are on fixed insulin regimens and do not adjust premeal insulin dosages, consistent
carbohydrate intake is the first priority (1,2,20). Individuals receiving insulin therapy should eat at consistent
times that are synchronized with the action time of their insulin preparation and with blood glucose results,
and insulin doses should be adjusted for the amount of food usually eaten or required (1-3). The decision to
adjust insulin doses should be based on a review of blood glucose records and discussion with the patient’s
physician and coordinating health care team.
Intensified insulin therapy (multiple daily injections or insulin pump therapy): The goal of intensified
insulin therapy is to bring the blood glucose levels as close to the normal range as is feasible for the
individual. Insulin infusion pumps mimic the normal physiologic insulin delivery and allow flexibility in meal
size and timing. Individuals that use rapid-acting insulin by injection or an insulin pump should adjust their
meal and snack insulin doses based on the carbohydrate content of the meals and snacks (2). Carbohydrate
counting, at an advanced level, can greatly increase flexibility in meal planning (21). The Diabetes Control and
Complications Trial found that individuals who adjusted their premeal insulin dosages based on the
carbohydrate content of meals had statistically significantly (0.5%) lower A1C levels than individuals who did
not adjust preprandial insulin dosages (22). Potential problems associated with intensified insulin therapy
include hypoglycemia and weight gain (2,23-25). Given the potential for weight gain to adversely affect
glycemia, dyslipidemia, blood pressure, and general health, the prevention of weight gain is desirable (2,26).
Reductions in blood glucose levels and A1C may cause hypoglycemia, which occurs more frequently in
individuals with type 1 diabetes (2). Patients on multiple-dose insulin (MDI) or insulin pump therapy should
do self-monitoring blood glucose (SMBG) at least prior to meals and snacks, occasionally postprandially, at