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66 Cards in this Set
- Front
- Back
Functions of Carbohydrates
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-Major fuel source for the body
-Primary fuel source for nervous system and RBC |
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How much carbs are stored in the body as glycogen?
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Limited amounts stored in body (as glycogen)
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general formula of carbs:
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General formula: (CH2O)n
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General classification of Carbs:
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Monosaccharides
Disaccharides Oligosaccharides Polysaccharides |
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types of monosaccharides:
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Glucose
Fructose Galactose |
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what is the principal monosaccharide in the body?
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glucose
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another name for glucose?
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blood sugar
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3 characterisctics of Fructose:
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Fructose:
Almost all is metabolized to glucose in the liver Found in fruit, honey, sucrose (table sugar) and high-fructose corn syrup Makes up ~8-10% of total energy intake in North America |
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3 characterisctics of Galactose:
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Not usually found free in nature
Usually bound with glucose (to form lactose) Converted to glucose in the liver |
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Disacharrides
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Disaccharides
Two monosaccharides held together by a glycosidic bond Condensation reaction (water is produced) Two forms of glycosidic bonds: Alpha glycosidic bond Beta glycosidic bond Maltose (Glucose + Glucose) --alpha bond Sucrose (Glucose + Fructose) --alpha bond Lactose (Galactose + Glucose) --beta bond |
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Sources of Disaccharides
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Sucrose: common table sugar (beet or cane), maple syrup
Lactose: primary sugar in milk and milk products Maltose: the breakdown of polysaccharides Enzymes: Sucrose: sucrase Lactose: lactase Maltose: maltase |
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3 types of complex carbs
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Oligosaccharides: raffinose & stachyose
Polysaccharides: Starch & Glycogen Dietary fiber |
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Characteristics of Oligoaccharides
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Contain 3 to 10 monosaccharides
Two primary ones are raffinose and stachyose (found in legumes such as beans) Not digested by human enzymes Therefore, metabolized by bacteria in the large intestine Beano®: enzyme preparation (made from mold) that breaks down many oligosaccharides in small intestine |
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Characterisitics of Polysaccharides
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Polysaccharides
Up to 1,000 or more monosaccharides bonded together Digestible: Starch Glycogen Indigestible: Fibers Soluble Insoluble |
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What kind of bonds does starch have?
2 types of starch? What is ratio of starch? |
Starch: incorporates alpha glycosidic bonds
Amylose--straight chain polymer Amylopectin--highly branched polymer Typical ratio is 1:4 (amylose to amylopectin) |
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properties of Amylopectin
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Amylopectin: increases blood glucose much more readily because numerous branches provide more sites for enzyme activity
Amylopectin: also forms very stable gel (i.e., retains water very well) |
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properties of glycogen
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Storage form of CHO for animals and humans
Structure similar to amylopectin but with more branching Therefore, more sites for enzyme action Found mainly in the liver (~400 kcal) and muscles(~1400 kcal) Muscle glycogen cannot yield blood glucose |
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what is the storage form of CHO for humans and animals?
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glycogen
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name the souble fiber and insoluble fibers?
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Insoluble fiber:
Cellulose, hemicellulose, lignin (non-CHO) Forms the structural part of plants Poorly fermented by the bacteria in the colon Soluble fiber: Gums, Pectins, Mucilages Found inside and around plant cells (i.e., is the glue) Sources: fruits, vegetables, rice bran, psyllium seed Fermented by bacteria in the colon |
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Bacterial Metabolism of Soluble Fiber:
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Produces short-chain fatty acids (SCFA)
Acetic acid (C=2) Propionic acid (C=3) Butyric acid (C=4) SCFA provide fuel source for intestinal cells Thus, enhance the health of the cells of the large intestine Also absorbed into the blood stream Soluble dietary fiber yields ~1.5 to 2.5 kcal/g |
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saliva contains...
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amylase
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8 benefits of dietary fiber
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Promotes softer, larger stool and regularity
Reduces hemorrhoids and diverticula Slows glucose absorption Reduces blood cholesterol by inhibiting cholesterol absorption Therefore reduces cardiovascular disease Reduces incidence of some cancers Aids in weight control (↓ kcals) Adults whose main CHO source is low-fiber foods: much more likely to develop diabetes |
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4 functions of Functions of Carbohydrate
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Functions of Carbohydrate:
Supplies energy to body cells Spares protein: if not enough CHO is consumed, body makes glucose from protein found in muscle tissues Prevents ketosis: if CHO intake is low you get incomplete metabolism of fat which results in formation of ketones Sweetener |
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Monosaccharide Metabolism...What happens in portal vein and what happens in the liver?
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Monosaccharide Metabolism
Portal Vein: Transports absorbed monosaccharides Delivers them to the liver Liver transforms fructose and galactose to glucose Liver can: Release glucose back to the blood stream Store glucose as glycogen Convert glucose to fatty acids |
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CHO Absorption...
Glucose and Galactose |
CHO Absorption
Glucose and Galactose Active absorption using a sodium pump Energy is expended to pump the sodium back out of the cell Going from low concentration to high Fructose Facilitated diffusion using a carrier No energy expended, therefore, slower process |
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Recommended CHO Intake?
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Recommended CHO Intake
Need 50 to 100 g of CHO/day to prevent ketosis Newly established RDA: 130 g/day for adults AMDR for CHO is 45 to 65% of TEI Reasonable goal: 45% of TEI from starch 55-60% of TEI from total CHO Current North American intake: 180-330 g of CHO/day (primarily from white bread, soft drinks, baked goods, potatoes) 50% of TEI is from CHO |
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Recommended Dietary Fiber Intake ??
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Recommended Dietary Fiber Intake
25 g/day for women; 38 g/day for men Standard: 14 g/1000 kcal Children: their age +5g/day Ave. U.S. intake: 14 to 19 g/day Half of breads/cereals should be whole grains! (current average: <1 serving daily) Too much fiber (>60 gm/d) will: require extra intake of fluid bind to some minerals (e.g., Zn and Fe) develop blockage of intestine fills the stomach of a young child too quickly |
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Recommendation for Simple Sugar Intake???
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Recommendation for Simple Sugar Intake
Sugar: low nutrient density Recommend no more than 10% of TEI from “added sugars “ Ave. U.S. intake: 16% of TEI Added sugars: sugars added to food and beverages during processing; does not include lactose from milk or fructose from fruit |
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4 Problems with High-Sugar Diets...
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Empty calories
(Soda has replaced milk) Calories add to excess weight Dental caries: Bacteria in mouth metabolize sugars into acids which dissolve and weaken tooth enamel High glycemic index. Blood glucose response of a given food |
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What factors influence Glycemic Index (GI)?
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Starch structure
Food processing (cooking, etc.) Physical structure (particle size) Dietary fiber content of the food Total fat and/or protein content of the food All of the above determine digestion rate of the CHO |
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What are the refernece points for Glycemic Index?
Ex Low, Intermediate, High. Also, reference for food glucose? |
Glycemic Index (GI)
Reference food glucose: 100 Low GI foods: <55 Intermediate GI foods: 55 → 70 High GI foods: >70 Examples of high GI foods: baked potatoes, mashed potatoes, short grain white rice, honey, jelly beans |
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Whay is glycemic load better than glycemic index?
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Glycemic Load (GL)
Better reflects a food’s effect on blood glucose than GI alone (because it accounts for amount of CHO consumed) GL = (GI/100) x amount of CHO found in a serving of the food Baked potato GL = .85 x 57 g CHO/serving = 48 |
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Reference points for lo, intermediate and high glycemic LOAD?
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Glycemic Load (GL)
Low GL foods: <10 Intermediate GL foods: 11→20 High GL foods: >20 |
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Effects of High GL CHO
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Stimulates the release of significant amounts of insulin
Insulin increases fat synthesis in liver Insulin increases blood triglycerides Insulin increases fat deposition in adipose tissue Insulin effects LDL (smaller particles) Insulin causes a more rapid return to hunger after a meal Insulin increases tendency for blood to clot Over time, muscle tissue may become resistant to the insulin, resulting in insulin resistance and, eventually, type 2 diabetes in some people |
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Describe Lactose Intolerance...
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Lactose Intolerance
Also referred to as “lactose maldigestion” Present in ~75% of world population Caused by reduction in lactase synthesis Lactose is undigested and not absorbed Lactose is metabolized by bacteria in large intestine causes gas, bloating, cramping, discomfort and diarrhea Primary lactose intolerance disease Secondary lactose intolerance disease |
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What To Do If You Are Lactose Intolerant
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Determine total amount you can tolerate
Nearly all with lactose intolerance can tolerate ½ to 1 cup of milk with meals Eat dairy with fat Cheese is usually tolerated well Yogurt is usually tolerated well because of live bacterial cultures Use of Lact-Aide Use low-lactose dairy products |
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What is the benchmark for comparing sweeteners ?
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sucrose
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5 types of nutritive sweeteners?
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High-fructose corn syrup
40 to 90 % fructose (usually ~55%) cornstarch is treated with acid and enzymes conversion of some of glucose into fructose same degree of sweetness as sucrose cheaper and used in many food products Brown sugar Maple syrup Honey – caution, not safe for infants, may contain Clostridium botulinum spores Sugar alcohols sorbitol, mannitol, xylitol ~1.5 to 3 kcal/g Absorbed and metabolized to glucose more slowly Large amounts can cause diarrhea Used in sugarless gums, candy, etc. Not readily metabolized by bacteria in mouth – less of a problem with dental caries |
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4 types non-nutritive sweeteners
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Saccharin
Aspartame Acesulfame-K Sucralose All yield little or no energy when consumed in typical amounts |
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what is not recommended for people with phenylketonuria (PKU)
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Aspartame
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what is the normal fasted blood glucose:
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between 70 and 99 mg/dl
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Symptoms of diabetes
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Symptoms:
Frequent urination Extreme thirst Hunger Fatigue Weight loss Eventual death |
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Diagnostic criteria for diabetes:
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Diagnostic criteria:
Diabetic – fasting blood glucose >125 mg/dl of blood Prediabetic – fasting blood glucose of 100 to 125 mg/dl of blood |
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New diabetes diagnostic tool:
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hemoglobin A1c
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Diabetes leads to ____ deatsh each yr
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~200,000
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diabetes effects ____ percent population
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7%
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Blood Glucose Control:
What is the role of the liver and the pancreas?? |
Liver: Main organ for regulating amount of glucose that enters bloodstream
Role of the pancreas: Releases insulin (when blood glucose is high) Releases glucagon (when blood glucose is low) Ratio of insulin to glucagon determines action Goal is to maintain blood glucose homeostasis |
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Blood Glucose Control:
Role of Pancreas |
Releases insulin (when blood glucose is high)
Releases glucagon (when blood glucose is low) Ratio of insulin to glucagon determines action Goal is to maintain blood glucose homeostasis |
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4 Functions of Insulin:
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Promotes glycogen synthesis and storage
Increases glucose uptake by the muscle cells, adipose cells, and others Reduces gluconeogenesis by liver Net effect: lowers blood glucose |
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4 Functions of Glucagon:
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Counteracts the effects of insulin
Breaks down glycogen in liver (but not in muscle) Enhances gluconeogenesis in the liver Net effect: raises blood glucose |
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Hormonal Influences on Insulin
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Epinephrine/norepinephrine:
Released by adrenal glands “Fight or flight” response Causes breakdown of glycogen Raises blood glucose Cortisol and growth hormone: increases gluconeogenesis raises blood glucose |
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What do most casesof Type 1 diabetes start with?
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Most cases begin with immunological disorder
An autoimmune reaction set off by a virus or a protein foreign to the body Immune system produces antibodies that attack the beta cells in the pancreas Results in gradual destruction of insulin-producing beta cells |
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When (what age) does type 1 diabetes usually start?
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late childhood, ages 8-14
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What will untreated type 1 diabetes lead to?
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Untreated Type 1 will lead to ketosis
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More than ___% of the diabetes cases in N. America are ______ diabetes
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Type 2
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Type 2 diabetes occurs at what age?
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Can occur at any age (most common is middle- to older-aged adults
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type 2 diabetes patients do/do not require insulin therapy initially in their disease?
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do not
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What is the initial problem in Type 2 diabetes?
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defective insulin receptors (i.e., insulin resistance)
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What percent of cases of Type 2 diabetes is related to obesity??
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80%
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Eventually, what percent of Type 2 diabetes pts will require insulin
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50%
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What meds are used in Type 2 diabetes?
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Glucophage – reduces glucose production by liver
Avandia – increases body’s response to its own insulin Precose – delays CHO digestion and absorption |
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Does type 2 diabetes often disappear when weight is lost?
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YES
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Consequences of Uncontrolled Blood Glucose... (7)
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Ketosis leading to ion imbalances, dehydration, coma, death
Degenerative diseases Nerve damage CVD Kidney disease Blindness Increased risk for wound infections and amputations |
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Describe Gestational diabetes...
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Brought on by pregnancy
During pregnancy, most women experience insulin resistance to some extent Helps make glucose more available to fetus In 4 to 7% of all pregnancies – gestational diabetes develops after 24th week – disappears within 6 weeks after delivery Babies tend to be larger at birth These women are at increased risk to develop Type 2 diabetes later |
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Describe Hypoglycemia...
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Reactive hypoglycemia
Occurs 2-4 hours after eating a meal high in CHO Possibly due to over-secretion of insulin? Fasting hypoglycemia Usually caused by pancreatic cancer or medications Leads to overproduction of insulin |
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dietary treament measures for type 1 diabetes...
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Dietary measures (to minimize swings in blood glucose):
3 regular meals and 1 or more snacks daily Regulated CHO:Protein:Fat ratio Diet rich in low glycemic load foods Ample fiber, esp. soluble fiber Moderate consumption of sugars with meals CHO counting (amount of CHO in each food) |