Longitudinal Orientation – Diabetes

Diabetes: associated with a relative or absolute impairment in insulin secretion, along with varying degrees of peripheral resistance to the action of insulin

Who should be screened for Diabetes?

USPSTF34 / All adults with a sustained blood pressure of greater than 135/80 mm Hg should be screened for diabetes.
Current evidence is insufficient to assess balance of benefits and harms of routine screening for type 2 diabetes in asymptomatic, normotensive patients.
AACE32 / All persons 30 years or older who are at risk of having or developing type 2 diabetes should be screened annually.
ADA8* / Testing to detect type 2 diabetes should be considered in asymptomatic adults with a BMI of 25 kg per m2 or greater and one or more additional risk factors for diabetes.
Additional risk factors include physical inactivity; hypertension; HDL cholesterol level of less than 35 mg per dL (0.91 mmol per L) or a triglyceride level of greater than 250 mg per dL (2.82 mmol per L); history of CV disease; A1C level of 5.7 percent or greater; IGT or IFG on previous testing; first-degree relative with diabetes; member of a high-risk ethnic group; in women, history of gestational diabetes or delivery of a baby greater than 4.05 kg (9 lb), or history of PCOS; other conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans).
In persons without risk factors, testing should begin at 45 years of age.
If test results are normal, repeat testing should be performed at least every three years

How is Diabetes diagnosed?

Based on 1 or 4 abnormalities:

  1. fasting plasma glucose
  2. random elevated glucose with sx
  3. abnormal glucose tolerance test
  4. HbA1C > 6.5 on 2 separate occassions

Let’s look at each of these:

FPG: - > or = 126 is Diabetes

-FPG >/= 100 but < 125 is Impaired Fasting Glucose

-fasting = no caloric intake for 8 hours

-preferred diagnostic test due to ease of use and lower cost

-normal FPG is < 100

-must be confirmed on a subsequent day (i.e., need 2 abnormal values for Dx)

-more likely to identify blood sugar problem in middle-aged obese subjects

Elevated random glucose WITH SX:

-random value must be > 200

-Sx: thirst, polyuria, weight loss, visual blurring

-must be repeated on subsequent testing (i.e., need 2 abnormals)

Oral Glucose Tolerance Test:

-more troublesome to perform and less reproducible

-more sensitive test than FPG

-75g sugar load (standardized)

-more likely to dx diabetes in lean patients

-if 2 hour BG > 200…Diabetes is dx’d

-if 2 hour BG between 140 and 199…Impaired glucose tolerance

-postprandial (OGTT) hyperglycemia seems to be more strongly associated with cardiovascular risk and mortality than FPG

-must be repeated on subsequent testing

-must be preceded by 8 hour fast

HbA1C:

-recently endorsed as screening test by AMA

-easy for patients, no fast required

-point-of-care testing (in office, similar to accucheck) not as standardized or reliable

-provides a 2 to 3 month average blood glucose concentration

-more expensive test

-influenced by the presence of renal failure and hemoglobinopathies

-must be verified on 2nd occasion

My patient’s labs are back, how do I categorize them?

Category / FPG / 2-h PG / HbA1C
Normal / <100 / <140 / <5.4
IFG / 100 – 125 / n/a / 5.7 – 6.4
IGT / n/a / 140 – 199 / 5.7 – 6.4
Diabetes / ≥ 126 / ≥ 200 / >6.5

FPG: fasting plasma glucose

IFG: impaired fasting glucose

IGT: impaired glucose tolerance

PG: postprandial glucose

What is the purpose of checking urine ketones?

-urine ketones can be checked on a urine dipstick

-if +  may indicate DKA

-if DKA, much more likely to be present in a type I diabetic

-type I diabetics have an insulin deficiency and thus are treated differently than type II (i.e., type I’s require insulin)

How do I differentiate type I from type II Diabetes?

Where diabetes is diagnosed, the diagnosis of Type 1 diabetes should be considered if:

  • ketonuria is detected, or
  • weight loss is marked, or
  • the person does not have features of the metabolic syndrome or other contributing illness”
  • c peptide: low in type I, high in type II; reflects amount of indogenous insulin and thus beta cell function; cost of test: $137

National Collaborating Centre for Chronic Conditions. Type 1 diabetes in adults. National clinical guideline for diagnosis and management in primary and secondary care. London (UK): RoyalCollege of Physicians; 2004.

See article in AAFP for further discussion of antibody testing.

Now that I’ve made the diagnosis, what do I do next?

Diabetics:

-target A1C goals in patients with type 2 diabetes should be tailored to the individual, balancing risk of microvascular complications with risk of hypoglycemia

-glycemic targets are set higher for older patients

-cardiac risk reduction is key: aspirin, smoking cessation, blood pressure control, reduction in serum lipids, diet and exercise)

-likelihood of successful diet is determined by initial fasting blood glucose:

FPG: 108 – 144 need to lose 10kg (16% initial body weight) to normalize

FPG: 216 – 252 need to lose 22 kg (35% initial body weight) to normalize

-any degree of weight loss is likely to improve glycemia and/or decrease need for meds

-exercise is beneficial independent of weight loss: increased responsiveness to insulin and delays progression from IGT to DM

-early institution of treatment at a time when the A1C is not significantly elevated, is associated with improved glycemic control over time and decreased long-term complications

-ADA recommends: start metformin and lifestyle intervention at time of dx of DM (titrate metformin to maximally effective dose over 1 to 2 months)

-if contraindication to metformin, short acting sulfonylurea (glipizide preferred) or TDZ (actos/pioglitazone preferred)

-insulin should be can be used as a first-line agent in those with A1C > 10, FPG > 250, random glucose consistently > 300.Insulin must be initiated immediately (consider hospitalization) for anyone with newly diagnosed Type 1 DM (ketone positive).

-aim for HbA1C as close to nondiabetic range as possible

-A1C > 7 suggests need for further adjustments in the regimen

-add another medicine if inadequately controlled (A1C > 7) within 2 – 3 months of iniating lifestyle intervention/metformin

Should medications be started in those with IFG or IGT?

-most effective: lifestyle modification

-drug therapy with metformin and acarbose (Precose) has been shown to prevent the progression of IGT to diabetes.

-31% reduction in the progression of diabetes in patients with IGT with metformin1

What are the community resources to help my patient manage their diabetes?

See “Diabetes Education Centers”…posted on faculty column

1 Knowler WC, Barrett-Connor E, Fowler SE, Hamman RF, Lachin JM, Walker EA, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346:393-403 Chiasson JL, Josse RG, Gomis R, Hanefeld M, Karasik A, Laakso M. Acarbose for prevention of type 2 diabetes mellitus: the STOP-NIDDM randomised trial. Lancet 2002;359:2072-7