Novelties in Diabetes Diagnosis and Management

Robert G. Spanheimer, M.D.
Gregory Doelle, M.D.
Zlatko Anguelov, M.D.
Vicki Kraus, A.R.N.P.
University of Iowa Hospitals and Clinics

First Published: Fall 2001
Last Revised: February 2003
Peer Review Status: Internally Peer Reviewed

Highlights:

• Diabetes mellitus is a disease characterized by heterogeneity in pathogenesis, natural history, response to therapy, and prevention.
• The improved understanding of diabetes has fostered a team approach to diabetes management whereby special attention is paid to technologies enabling individually adjusted, around-the-clock insulin delivery.
• The diagnostic criteria for hyperglycemia have been substantially revised.

History: The time when diabetes mellitus was regarded simply as an insulin-deficient, hyperglycemic disease is long gone. Throughout the last four decades, basic and clinical research has revealed diabetes to be a complex metabolic disorder. Classification of diabetes is thus a complex and changing issue. Yet, appropriate management depends strictly on correctly identifying the type of diabetes in individual patients.

According to the latest definition, proposed by the American Diabetes Association's Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, diabetes mellitus is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Thus, diabetes entails heterogeneity in pathogenesis, natural history, response to therapy, and prevention. In addition, different genetic and environmental factors can result in forms of diabetes that appear phenotypically similar but have different etiologies.

The improved understanding of diabetes has, on the one hand, fostered a team approach to diabetes management in order to meet its many challenges. On the other hand, it has allowed for case-tailored management plans that reduce both acute and chronic complications. In this vein, special attention has been paid to technologies enabling around-the-clock insulin delivery that is individually adjusted to fluctuations in body glucose level.

New facts: Severely insulin-deficient, ketosis-prone patients fall into a class called type 1 diabetes. They represent about 5% to 10% of all diabetic patients. Their disease is primarily due to autoimmune-mediated destruction of the pancreatic b-cells. The incidence of type 1 diabetes has been constant over the last four decades.

The class labeled type 2 diabetes includes the most prevalent form of the disease, which results from insulin resistance combined with an insulin secretory defect. Its incidence has increased dramatically in the last four decades, taking on epidemic proportions. All other types of diabetes are secondary to conditions with specific, identifiable etiologies or to pregnancy.

The revised diagnostic criteria for hyperglycemia are set within the following range: fasting plasma glucose (FPG) < 110 mg/dl is the cutoff point for normal fasting glucose; FPG > 110 but < 126 mg/dl is regarded as impaired fasting glucose; and FPG > 126 mg/dl is a provisional diagnosis of diabetes. The same reading must be confirmed on a subsequent day and with other PG measures.

The recommended treatment goal cutoff remains at FPG < 120 mg/dl. Another test recommended for monitoring glycemia and identifying the risk of diabetic complications is HbA_1c measurement. HbA_1c is a glycosylated fraction of hemoglobins. The recommended treatment goal is to maintain HbA1_c < 7%.

Two major studies during the past decade have shown that there is a clear correlation between good plasma glucose (PG) control and a lower incidence of diabetic complications. Thus, the secret to successfully managing diabetic patients is steady PG control. Patients with type 1 diabetes require insulin for glucose control and survival. Patients with type 2 diabetes are usually controlled with diet, oral medications, and in many cases, insulin.

Criteria for the diagnosis of diabetes mellitus 1. Symptoms of diabetes plus casual plasma glucose concentration 3 200 mg/dl (11.1 mmol/l). Casual is defined as any time of day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss. or 2. FPG 3 126 mg/dl (7.0 mmol/l). Fasting is defined as no caloric intake for at least 8 hours. or 3. 2-h PG 3 200 mg/dl (11.1 mmol/l) during an oral glucose tolerance test (OGTT). The test should be performed as described by WHO, using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water. ---------- In the absence of unequivocal hyperglycemia with acute metabolic decompensation, these criteria should be confirmed by repeat testing on a different day. The third measure (OGTT) is not recommended for routine clinical use.

Practice: Continuous glucose monitoring is available at UI Hospitals and Clinics. Both continuous subcutaneous insulin infusion (CSII) using an insulin pump and multiple daily insulin injection therapy are regarded as effective means of achieving near-normal PG levels in patients with type 1 diabetes. The therapy chosen is based on patient preference. Glucose profiles are then available for review and become the basis for making recommendations about therapy. However, with the improvement of insulin-pump technology, CSII is increasingly recommended as the most effective way of intensifying insulin therapy for many type 1 diabetes patients.

Patients may be monitored through the continuous glucose monitoring program using a glucose sensor that makes 288 tissue-fluid glucose measurements a day, or roughly every 5 minutes for 72 hours. The glucose sensor measures tissue fluid glucose and saves the values in a monitor that later downloads the data into a computer. In this way daily glucose profiles may be obtained for each monitored patient.

Intensive management is assured for patients who opt for the insulin pump. It administers insulin subcutaneously at rates determined and periodically calibrated by the patient based on his or her glucose measurements. A basal insulin is programmed into the pump and runs continuously throughout the day and night. Bolus doses of insulin are given through the pump as well, but are programmed by the patients when they need it before meals or to correct high PG levels. At UI Hospitals and Clinics, treatment involves a short-acting insulin in order to avoid unpredictable absorption rates.

At this time, glucose measurement and insulin administration work in an open-loop system; that is, the patient makes the changes in insulin dosing according to fluctuations in glucose levels. A major breakthrough will occur with the invention of software that will change the open-loop system into a closed-loop one. In this situation both the sensor and the pump will be electronically linked to self-calibrate the insulin delivery based on changing glucose levels.

Experience with insulin-pump therapy indicates that candidates for CSII must be strongly motivated to improve glucose control. They also should be willing to work with the diabetes management team in assuming responsibility for their day-to-day care. Among patients who meet the above requirements, a clear decrease in the frequency of hyperglycemia and hypoglycemia is noticed. Another unquestionable benefit of the insulin pump is that it provides more lifestyle flexibility, especially regarding the number of meals eaten and the amount of exercise performed per day.

Comprehensive management of diabetes patients at UI Hospitals and Clinics is based on a team approach. A team is composed of an endocrinologist, nurse, and dietitian. Five diabetes clinics are offered per week, and an endocrinology consult team is available 24 hours a day, seven days a week.

A special emphasis is placed on patient education: a group diabetes self-management education program is offered weekly by certified diabetes educators. The program is recognized by the American Diabetes Association. Diabetes nursing staff provides a telephone follow-up of patients to assist them with the PG control. Telephone follow-up is provided for patients who are newly diagnosed, have a change in their diabetes regimen, or are having problems achieving PG control goals. Nurses and dietitians also provide individual diabetes education at the bedside for hospitalized patients and in clinics for outpatients.

See related Provider Textbooks about Internal Medicine.

See related Provider Topics Diabetes, Endocrine System (Hormones), Endocrinology, Food, Nutrition and Metabolism, Immune System/AIDS, Internal Medicine or Seniors' Health.

See related Patient Textbooks about Internal Medicine.

See related Patient Topics Diabetes, Endocrine System (Hormones), Endocrinology, Food, Nutrition and Metabolism, Immune System/AIDS, Internal Medicine or Seniors' Health.

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