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hyperglycemia (by inhibition of α-cells) and prevents recurrence of hypoglyce-

mia (by inhibition of β-cells). When euglycemia is achieved, glucagon not only

stimulates β-cell but also δ-cell which in turn results in inhibition of its own

secretion by insulin as well as by somatostatin, respectively. However, the

effect of insulin on regulation of δ-cell function is not well defined. Incretins

play an important role in facilitating the cross-talk among islet cell as GLP1

stimulates β-cell and inhibits α-cell. Further, GIP stimulates α-cell in the pres-

ence of hypoglycemia. Therefore, the cross-talk among the islet cells is crucial

to maintain euglycemia in a healthy individual. The cross-talk among the islet

cells is depicted in the figure given below (Fig. 12.1).

9. What are the characteristic features of type 1 diabetes mellitus?

Young age of onset, the presence of islet autoimmunity, and absolute insulin defi-

ciency are the characteristic features of T1DM. Type 1 diabetes has trimodal dis-

tribution of age with first peak at 3–6 years, second at peripubertal age, and finally

at 35–40 years of age. Absolute insulin deficiency is the hallmark feature of T1DM

and manifests as severe osmotic symptoms, sarcopenia, and ketosis/ketoacidosis.

Approximately, 30–40 % of patients present with DKA, while the rest have hyper-

glycemia and asymptomatic ketonemia without acidosis. These patients require

insulin since the diagnosis of diabetes. The presence of islet autoimmunity in these

patients is a strong pointer toward immune-mediated β-cell destruction, and mul-

tiple islet autoantibodies (≥2) are usually present in these patients.

10. Is there a phase of prediabetes in patients with type 1 diabetes?

Evolution of T1DM occurs through series of stages that begins with the

development of autoimmunity in genetically predisposed individuals.

Capillary network

Alpha cells

Beta cells

Delta cells

Glucagon

Glucagon

Glucagon

Insulin beta cells

Insulin

Insulin

Insulin

Somatostatin

Somatostatin

Somatostatin

Delta cells

Somatostatin

Alpha cells

Glucagon

Fig 12.1 Depicting cross-talk among different islet cells in the regulation of glucose
homeostasis

12 Diabetes in the Young