What is the role of lab tests in the workup of glucose intolerance disorders?

Updated: Jun 28, 2019
  • Author: Samuel T Olatunbosun, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Answer

Workup for the diagnosis of glucose intolerance include plasma glucose level, oral glucose tolerance testing, other screening tests, urinalysis, complete blood count, lipid profile, liver function testing, and measurement of serum electrolytes, BUN, creatinine, uric acid, and blood gases.

Urinalysis is important because ketonuria and massive glycosuria are indicators of acute decompensation. Significant proteinuria may be present in patients with diabetic nephropathy. Abnormalities of specific gravity and pH can be found in patients with uremia. Urine microalbumin is a marker of early renal impairment and endothelial dysfunction.

A complete blood cell count is obtained, because an increased white blood cell count is common during acute infection. Ketoacidosis also is a cause of leukocytosis.

lipid profile is necessary to detect an increased triglyceride level, often a reflection of poor glycemic control that may normalize on attainment of euglycemia. Other lipid abnormalities, such as increased total cholesterol and low-density lipoprotein levels, are commonly found.

Liver function tests assessing baseline liver function are used to exclude hepatic disease prior to commencing certain antihyperglycemic agents (eg, biguanides, thiazolidinediones). Periodic measurements are required during treatment with thiazolidinediones. Liver cirrhosis is a cause of glucose intolerance.

Serum electrolytes, BUNcreatinineuric acid, and blood gases are evaluated, because during acute decompensation, metabolic derangement from loss of water, sodium, potassium, and other electrolytes, as well as anion gap and osmolality abnormalities, are very common. Normal renal and hepatic function must be confirmed before therapy is started with some oral antidiabetic agents.

C-peptide profile is needed, because an undetectable plasma level indicates type 1 diabetes (in the absence of hypoglycemia). C-peptide profiling may also be helpful in deciding treatment in some cases of type 2 diabetes. It is not routinely used in clinical practice.

Increased levels of plasma plasminogen activator inhibitor type 1, a marker of impaired fibrinolysis, are frequently found in patients with glucose intolerance and are a correlate of insulin resistance syndrome. [43, 44]  An increased plasma homocysteine level is a risk factor for atherosclerosis. The homocysteine level should therefore be measured in selected patients.


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