To generate the report, Norman can use the following program:

```

#include <stdio.h>

int main() {

int n, i, insulin = 0;

char treatment;

float percentage;

printf("********* DISTRICT HEALTH CLINIC ********* ****Diabetes Treatment Report ****\n");

printf("Please enter the number of patients:");

scanf("%d", &n);

printf("\n**** TREATMENT TYPE ****\n");

printf("Insulin 1\nMetaformin M\n");

int patient_id[n];

char treatment_type[n];

for (i = 0; i < n; i++) {

printf("\nEnter patient ID: ");

scanf("%d", &patient_id[i]);

printf("Treatment Type: ");

scanf(" %c", &treatment_type[i]);

if (treatment_type[i] == '1') {

insulin++;

} else if (treatment_type[i] != 'M') {

printf("You entered an invalid treatment code\n");

i--;

}

}

percentage = ((float)insulin / n) * 100;

printf("\nThe total number of insulin patients: %d The percentage of insulin patients %.1f%%\n", insulin, percentage);

printf("\nEnter option to print a list-> I for Insulin, M for Metaformin: ");

scanf(" %c", &treatment);

printf("Patient ID\n");

for (i = 0; i < n; i++) {

if (treatment_type[i] == treatment) {

printf("%d\n", patient_id[i]);

} else if (treatment == 'I' && treatment_type[i] == '1') {

printf("%d\n", patient_id[i]);

} else if (treatment != 'M' && treatment != 'I') {

printf("You entered an invalid treatment code\n");

break;

}

}

return 0;

}

```

The program starts by displaying a header and prompting the user to enter the number of patients. Then, it displays the treatment options and asks the user to enter the patient ID and treatment type for each patient. While doing so, it keeps track of the number of patients receiving insulin treatment.

After all patients have been entered, the program calculates the total number and percentage of patients receiving insulin treatment and displays them.

Finally, the program prompts the user to enter a treatment code to display a list of patients receiving that treatment. It uses a linear search algorithm to find the patients with the specified treatment type and displays their IDs. If the user enters an invalid treatment code, the program displays an error message.

I hope this helps :)