Insulin Glargine in Type I Diabetes Mellitus> Main Study "AT.LANTUS": A Trial Comparing Lantus Algorithms to Achieve Normal Blood Glucose Targets in Subjects With Uncontrolled Blood Sugar. Sub-study: "HALT"(Hypoglycaemia Avoidance With Lantus Trial)

Primary objective: AT.LANTUS main study\* * To determine the optimal treatment algorithm for insulin glargine based on the incidence of severe hypoglycaemia.(\*Target Number of patients for the main study:2346) HALT Sub-study\*\* * To test the hypothesis that titration regimens involving insulin glargine are associated with changes in the rate of symptomatic hypoglycaemic episodes together with changes in Fear of Hypoglycaemia as measured by the HFS-98 Questionnaire in Type I diabetes.(\*\*Target Number of patients for the Sub-study: 250) Secondary objectives: AT.LANTUS main study To determine: * the incidence of symptomatic, asymptomatic and nocturnal hypoglycaemia with each treatment regimen * the difference in glycemic control as measured by HbA1c and fasting blood glucose with each treatment regimen * the difference in glycemic control as measured by HbA1c and fasting blood glucose between baseline and end of treatment * the safety on the use of insulin glargine in each treatment algorithm * the change in subject weight with each treatment regimen * the change in insulin doses with each treatment regimen * the change in Diabetes Treatment Satisfaction (Diabetes Treatment Satisfaction Questionnaire, sub-study only) with each treatment regimen HALT Sub-study (baseline to study end) * To estimate the relationship between change in HbA1c and incidence of hypoglycaemia * To examine the effect of insulin glargine on Quality of Life (EQ-5D) in relation to incidence of hypoglycaemia * To examine the effect of insulin glargine on the Hospital Anxiety and Depression Scale (HADS) in relation to the incidence of hypoglycaemia * To examine the use of the Prescription Plan versus standard management (no Prescription Plan)