Читать книгу The Diabetes Ready Reference for Health Professionals - Kathryn Mulcahy - Страница 7

DIAGNOSIS OF DIABETES

I. CRITERIA FOR DIAGNOSIS

A. Type 1 and type 2 diabetes

1. Nonpregnant adults

a. Casual plasma glucose ≥200 mg/dl (≥11.1 mmol/l) plus classic symptoms OR Fasting plasma glucose (FPG) ≥126 mg/dl (≥7.0 mmol/l) OR 2-hour plasma glucose (PG) ≥200 mg/dl (≥11.1 mmol/l) on 75-g oral glucose tolerance test (OGTT) (OGTT no longer routinely recommended)

b. Each of these tests should be confirmed by an additional test on a subsequent day unless unequivocal hyperglycemia exists. This can be the same test (e.g., two FPGs) or a different test (e.g., random blood glucose followed by FPG).

c. OGTT rarely needed to diagnose type 1 diabetes

2. Children

a. Same as for nonpregnant adults (see above)

b. OGTT contraindicated in infants and young children

B. Gestational diabetes mellitus (GDM)

1. 1-hour screen of those at risk using a 50-g glucose load performed between 24th and 28th week of gestation unless otherwise indicated. If screen shows glucose ≥140 mg/dl (≥7.8 mmol/l), diagnosis confirmed based on 100-g OGTT resulting in any two or more of the following:

Fasting	95 mg/dl (≥5.3 mmol/l)
1 hour	≥180 mg/dl (≥10.0 mmol/l)
2 hour	≥155 mg/dl (≥8.6 mmol/l)
3 hour	≥140 mg/dl (≥7.8 mmol/l)

C. Pre-diabetes

1. Impaired fasting glucose (IFG): FPG ≥100 mg/dl (≥5.6 mmol/l) and <126 mg/dl (<7.0 mmol/l)

2. Impaired glucose tolerance (IGT): diagnosis based on 75-g OGTT, 2-hour glucose ≥140 mg/dl (≥7.8 mmol/l) and <200 mg/dl (<11.1 mmol/l)

II. INDICATIONS FOR SCREENING/
DIAGNOSTIC TESTING

A. Type 1 diabetes

1. No indications for screening

2. Diagnostic testing indicated when classic signs and symptoms are present (e.g., polyuria, polydipsia, weight loss, polyphagia, and blurred vision)

B. Type 2 diabetes

1. Consider screening at 3-year intervals adults over the age of 45, particularly with a BMI ≥25 kg/m². Screen at a younger age those who are overweight and have one or more of the following risk factors:

a. Overweight (BMI ≥25* kg/m²) (* may not be correct for all ethnic groups)

b. Family history of diabetes (parents or siblings)

c. Physically inactive

d. Race/ethnicity (e.g., Native Americans, African Americans, Latinos, Asian Americans, Pacific Islanders)

e. Previously identified pre-diabetes (IFG and/or IGT)

f. History of gestational diabetes or delivery of a baby >9 lb

g. Hypertension (>140/90 mmHg in adults)

h. HDL cholesterol <35 mg/dl (0.90 mmol/l) and/or a triglyceride level >250 mg/dl (2.82 mmol/l)

i. Polycystic ovary syndrome (PCOS)

j. History of vascular disease

2. Screen children and adolescents who are at significant risk for type 2 diabetes. Test every 2 years after the age of 10, or at the onset of puberty if it occurs at a younger age, if:

a. BMI >85th percentile for age and sex, OR weight for height >85th percentile, OR weight >120% of ideal for height

b. Have a family history of type 2 diabetes in first- and second-degree relatives

c. Belong to certain race/ethnic groups: Native Americans, African Americans, Hispanic Americans, Asians/South Pacific Islanders

d. Have signs of or conditions associated with insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, PCOS)

C. Gestational diabetes mellitus (GDM)

1. Risk assessment at first prenatal visit

2. If high risk, glucose testing as soon as feasible. High risk includes:

a. Obesity

b. Previous history of GDM

c. Glycosuria

d. Diabetes in first-degree relative

3. If not high risk, glucose testing is recommended at 24–28 weeks’ gestation for all pregnant women except those considered low risk for GDM (see below).

4. Low-risk status for GDM requires no glucose testing. This status is limited to those women who meet all of the following:

a. Age <25 years

b. Normal weight before pregnancy

c. Member of an ethnic group with a low prevalence of diabetes

d. No history of abnormal glucose tolerance

e. No history of poor obstetric outcomes

5. Screening test: plasma glucose (PG) 1 hour after 50-g glucose load

a. PG >140 mg/dl (>7.8 mmol/l) identifies ~80% of women with GDM.

b. PG >130 mg/dl (>7.2 mmol/l) identifies ~90% of women with GDM.

c. With either result, diagnostic testing for GDM is indicated.

III. PREPARATION FOR THE OGTT

A. OGTT is performed using a 75- or 100-g oral glucose load in the morning after a noncaloric 8-hour fast. Water is allowed but not coffee or smoking.

B. Test should be performed on an individual without underlying illness and/or interfering drugs. OGTT is not appropriate for patient who is malnourished, on a restricted-carbohydrate diet, or with acute or chronic illness.

C. Patient should be ambulatory and not on bed rest, hospitalized, or immobilized. During the test, patient should be resting comfortably.

D. Patient should consume an unrestricted diet containing at least 150 g carbohydrate daily for 3 days before test.

IV. OTHER DIAGNOSTIC PROCEDURES

A. C-peptide (see Glossary)

B. Islet cell antibody (ICA) and antibodies to glutamic acid decarboxylase (GAD) (see Glossary)