July 02, 2007

Diabetes Mellitus: Water Water Everywhere

Samuel Taylor Coleridge in his poem 'The Rime of the Ancient Mariner' said ' Water, water, every where, Nor any drop to drink'. A similar type of situation occurs in a human disease where sugar is plentiful in the blood and other tissues, but the cells themselves go hungry. Diabetes Mellitus is such a disease where there is 'starvation in the midst of plenty'.

Diabetes is a group of disorder in which there is hyperglycemia. This rise in plasma glucose level can be brought about by a decrease in (or absent) insulin levels, insulin resistance (insulin is there or may be even raised-but the cells are refractory to its presence), or counter-regulatory hormone (such as glucagon) excess. Presently diabetes is classified into 4 types, on the basis of the pathologic processes that leads to hyperglycemia. Type2 DM accounts for about 90% of all diagnosed cases while type1 diabetes accounts for about 5-10%.

In type1DM, the pancreatic beta cells of the islets of Langerhans are destroyed. These cells secrete insulin into the blood stream. These cells may die as a result of an autoimmune process (type1A) or the cause of their death may not be known (type1B or idiopathic). In type1A DM the destruction is due to an autoimmune insult on a person genetically predisposed to it (e.g. HLA DR3 and/DR4 haplotype present on chromosome6) or persons exposed to environmental toxins like bovine milk protein etc.

As the insulin forming cells of the pancreas are gone in type1 diabetes, the treatment naturally consists of substituting insulin. It is given by subcutaneous injection. Typically a long acting insulin such as ultralente or glargine insulin is given twice a day. One shot of it is given during breakfast and another during supper. They help maintain a steady basal supply of insulin. Short acting insulins like lispro insulin are added to this regimen during breakfast, lunch and supper time to tide over glucose surges during mealtime (thus mimicking physiological insulin release during these times). The average insulin requirement in type1 diabetes is about 0.5-1.0 unit insulin/kg (weight of the patient)/day. But this is only a rough estimate. The dose should be titrated by taking several (about 6-8 in a day!) measurements of SMBG (self monitoring of blood glucose: using glucowatch or other devices).

The diet should also be carefully watched (strict carbohydrate intake as used to be advocated in the past is no longer recommended) and the patient should be acquainted with the disease and its manifestations and complications, in addition to the pharmacotherapy by insulin.

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