Sir,

Hair of a person may represent an easily accessible and non- invasive tissue for the study of hyperglycemia. Assessing the amount of glycation in hair apart from being readily acceptable to the patients provides fairly accurate and reliable information regarding the degree, the duration of hyperglycemia, and the associated microvascular complications.

Unlike glycosylated hemoglobin that mirrors glycemic control preceding 8 to 12 weeks, analysis of hair-glycation can help one to monitor the diabetic\'s metabolic balance for longer time periods. A study showed a significant correlation between glycosylation of the proximal 4 cm of hair (representing 16 weeks at an assumed average rate of hair growth of 0.37 mm/day) and the glycosylated hemoglobin (HbA1c).\[[@ref1]\] The level of glycosylation of hair is known to be independent of duration of the disease, age, sex, and race of the patient and color of the hair.

Being stable along the length of the hair from scalp to tip, a sufficiently long hair sample enables us to record a long term record of degree of hyperglycemia.

Hair samples of 12 cm long may correspond to about one year\'s tissue glycosylation and diabetic microvascular complications.

A novel dot-block immunochemical assay of hair of diabetics showed significant correlations in amounts of blood glucose (BG) vs. HbA1~c~, BG vs. early glycation products (EGAs) and HbA1~c~ vs. EGAs. In the same study, type1 diabetics of acute onset displayed nearly similar EGAs levels in their proximal 0-9 cm hair as did type1 diabetics with long-established diabetes. This reinforces the notion of long and insidious etiology of type 1 diabetes.\[[@ref2]\] Proteic sulphur levels and furosine in the hair diabetics also closely correlate with HbA1c.

Significant rate of hair loss may reflect impaired glycemic control. Poor circulation affecting the production of new strands or filaments resulting in thinner and sparsely located hairs, effects of antidiabetic drugs, physiological and psychological stress and anxiety, dehydration etc are some of the factors that are responsible for increasing hair loss in diabetics. A French study on 6,00,000 people apparently unaware of the fact that they are suffering from type 2 diabetes showed that they had diffuse hair loss.\[[@ref1]\]

An endogenous modification in the labile structure of the matrix at established intermediate filament linkage sites is noted in the molecular structure of α-keratin of hair of diabetics. Hair shaft diameter is also significantly reduced in diabetics. A study showed that diabetic female children had smaller bulb diameters and diabetics of both sexes had reduced shaft diameters compared to normal children.\[[@ref3]\] Darker eyebrows with graying scalp hair in males may also point to diabetes.

Diabetics are known to have elevated hair K, Na, Hg and decreased Ca, Mg, Zn.\[[@ref4]\] Glucose intolerance is also known to perturb Cr metabolism. Hair arsenic has shown a bearing over glycemic control in pregnant subjects.\[[@ref5]\]

Hair may be the universal index of hyperglycemia reflecting the control of diabetic state. It may also unmask a hitherto unknown diabetic, enabling clinicians to start early therapy.
