Diabetes Investigations And Diagnosis
Diabetes Insipidus
There is deficiency of vasopressin, antidiuretic hormone(adh), secreted by the posterior pituitary. In its absence, absorption of water from the distal renal tubule is defective. There is excessive loss of water. Urine is dilute and large in quantity.
Symptoms
There is polyuria , nocturia and compensatory polydipsia.
Sign.
Dehydration is uncommon and only occurs if fluid intake is impaired.
Investigation
Urine osmolality is low and plasma osmolality is high.
When fluids are restricted water deprivation test), urine osmolality does not rise(normally it does). This test should be carried out in the hospital and patient’s weight should be monitored, as there is risk of severe dehydration.
If vasopressin (pitressin) is injected, urine osmolality rises.
Diabetes Mellitus
It is a metabolic disorder characterized by hyperglycemia due to deficiency or diminished effectiveness of insulin. Glycosuria may or mau not be present.
Types.
A. Primary Diabetes Mellitus
There is no apparent cause. This is the most common variety. It is further divided into two subtyeps.
1. Type 1 Diabetes Mellitus, Previously called insulin dependent Diabetes Mellitus (IDDM).
2. Type 2 Diabetes Mellitus, previous called non-insulin dependent Diabetes Mellitus (NIDDM)
B. Secondary Diabetes Mellitus
Diabetes occurs as a manifestation of another disease. It is either due to disease of pancreas or due to presence of excessive amount of insulin antagonists eg, growth hormone, glucocorticoids.
Causes
Pancreatitis
Hemochromatosis
Carcinoma Pancreas
Pancreatectomy
Cystic Fibrosis
Thyrotoxicosis
Pregnancy
Cushing’s syndrome
Pheochromocytoma
Acromegaly
Symptoms
There are three classical symptoms; Polyuria, Polyphagia, Polydipsia. Patient may present with symptoms of complications.
Signs
There are no signs due to diabetes itself. Signs are present when patient develops complications.
Investigation
Diagnosis of diabetes is based on abnormal blood glucose levels. Fasting plasma glucose level of more than 125mg/dl or 2 hours postparandial plasma glucose level of more than 200 mg/dl on more than occasion in a symptomatic patient is taken as diagnostic of diabetes mellitus. If level are equivocal, a formal glucose tolerance test is required.
Complication of Diabetes Mellitus
Acute Complications
1 Diabetic ketoacidosis
2 Nonketotic hyperosmolar state
Chronic Complication
A Microvascular
1 Diabetic nephropathy
2 Diabetic neuropathy
3 Diabetic retinopathy
4 Early cataract
B Macrovascular
1 Coronary artery disease
2 Peripheral vascular disease
3 Cerebrovascular disease
C Other
1 Increased risk of infection(carbuncle, diabetic foot, pneumonia, tuberculosis, moniliasis)
2 Dermatologic manifestation(necrobiosis lipoidica, diabeticorum, lipoatrophy/lipodystrophy, as a complication of insulin therapy)
